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Discussion Starter · #1 ·
I took my car to AutoZone to have the check engine light scanned to make sure it was an oxygen sensor because I just bought the car and the previous owner told me I needed to extend a harness better because it has long tube headers. Now when they went to run the codes they said they couldn't pull any of them and I took it to two AutoZone's and they both had the same problem could I have a faulty ECU?
Also do they sell oxygen sensor harness extensions or will I be forced to splice into the wires to extend it if so can someone please provide me a link to the part?
 

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I took my car to AutoZone to have the check engine light scanned to make sure it was an oxygen sensor because I just bought the car and the previous owner told me I needed to extend a harness better because it has long tube headers. Now when they went to run the codes they said they couldn't pull any of them and I took it to two AutoZone's and they both had the same problem could I have a faulty ECU?
Also do they sell oxygen sensor harness extensions or will I be forced to splice into the wires to extend it if so can someone please provide me a link to the part?
you can not splice into the wires from the sensor to the first plug they are part of what the resistances are for the ecu.
the 2 small wires from sensors are ecu signal and switched earth, the two larger ones are the heater wires, you must use correct sensors and to be honest if they do not have bosch stamped on the sensor then they will be cheap rubbish ones that last two minutes have seen ebay ones says bosch on box but not on sensor and they can last days or months. the designed life of a sensor is around 60,000 miles as is the cat
 

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Discussion Starter · #4 · (Edited)
I took my car to AutoZone to have the check engine light scanned to make sure it was an oxygen sensor because I just bought the car and the previous owner told me I needed to extend a harness better because it has long tube headers. Now when they went to run the codes they said they couldn't pull any of them and I took it to two AutoZone's and they both had the same problem could I have a faulty ECU?
Also do they sell oxygen sensor harness extensions or will I be forced to splice into the wires to extend it if so can someone please provide me a link to the part?
you can not splice into the wires from the sensor to the first plug they are part of what the resistances are for the ecu.
the 2 small wires from sensors are ecu signal and switched earth, the two larger ones are the heater wires, you must use correct sensors and to be honest if they do not have bosch stamped on the sensor then they will be cheap rubbish ones that last two minutes have seen ebay ones says bosch on box but not on sensor and they can last days or months. the designed life of a sensor is around 60,000 miles as is the cat
If I can't splice into the sensor, how do people run long tube headers ??
What oxygen sensor can I get that will have long enough wires because the stock does not reach.
I just watched a YouTube video of a guy who said exactly what I did to do and he did that with his mini he just placed in the right gauge wire into the action sensor for the upstream and extended it and it worked just fine are you positive about this are you saying this from experience are you saying this as a possibility it might do to the word heated wire
 

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I took my car to AutoZone to have the check engine light scanned to make sure it was an oxygen sensor because I just bought the car and the previous owner told me I needed to extend a harness better because it has long tube headers. Now when they went to run the codes they said they couldn't pull any of them and I took it to two AutoZone's and they both had the same problem could I have a faulty ECU?
Also do they sell oxygen sensor harness extensions or will I be forced to splice into the wires to extend it if so can someone please provide me a link to the part?
No, the early cars (up to 2006) were OBD compliant and not OBD 2 which is what most people expect and try to use, but does not work. BMW didn’t comply as soon as most with the industry standards.

You need the right diagnostics for the car.
 

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Discussion Starter · #7 ·
I took my car to AutoZone to have the check engine light scanned to make sure it was an oxygen sensor because I just bought the car and the previous owner told me I needed to extend a harness better because it has long tube headers. Now when they went to run the codes they said they couldn't pull any of them and I took it to two AutoZone's and they both had the same problem could I have a faulty ECU?
Also do they sell oxygen sensor harness extensions or will I be forced to splice into the wires to extend it if so can someone please provide me a link to the part?
No, the early cars (up to 2006) were OBD compliment and not OBD 2 which is what most people expect and try to use, but does not work. BMW didn’t comply as soon as most with the industry standards.

You need the right diagnostics for the car.
Your saying it's obd1 not 0bd2 ?
 

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If I can't splice into the sensor, how do people run long tube headers ??
What oxygen sensor can I get that will have long enough wires because the stock does not reach.
I just watched a YouTube video of a guy who said exactly what I did to do and he did that with his mini he just placed in the right gauge wire into the action sensor for the upstream and extended it and it worked just fine are you positive about this are you saying this from experience are you saying this as a possibility it might do to the word heated wire
many years ago now i went on a bosch seminar as part of working at a main agents ie we all had to do these refresher courses and their view on not mine their view on it was this, never alter a 02 sensor wires from the sensor to the plug as this is all part of how they design them to read a given resistance,, bare in mind the ecu and 5v or 12v rail needs accurate component resistances to run correctly,,, ie these cheap chinese 02 sensors with wires and no sockets are just wrong as even the wrong material used in the pins will change the given resistance needed for the ecu to control all the surfaces correctly,, ie all sensors are designed and produced to give a set parameter to how they are used and all ecu software and hard ware is also designed the same way,, the way around this is to extend the cable with in the wiring lomb of car but you must count the strands of wire and mimic the amount and size of wire for a perfect out come, if you use bigger wire less or smaller wire will have affect on signal. they also said 60k and sensors are getting to end of life, how come the stock sensor dont reach cant see when it left the factory with a stock sensor they just did not connect ot because it would not reach. more like not got the right sensor now or someone has hacked the wiring on the car maybe,
 
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another added little point,

An oxygen sensor will typically generate up to about 0.9 volts when the fuel mixture is rich and there is little unburned oxygen in the exhaust. When the mixture is lean, the sensor's output voltage will drop down to about 0.1 volts. When the air/fuel mixture is balanced or at the equilibrium point of about 14.7 to 1, the sensor will read around 0.45 volts.

so slight differences in resistance makes a big impact as the system runs on very very low power even running the wiring close to a cam position sensor ie hall effect can cause interference and make the engine run rich or weak that can on force induction as yours is to big melt downs, so this kind of job must me done correctly, some diesels will sort of run fine by doing what you asking but if were my money on the line would fit genuine 02 sensors and the correct way,, want to prove this point further go in to a rolling road tuner and ask him what his feelings are on it, they see non stop what cheap bodged sensors do to their mapping process.
 

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below is everything you need to know about 02 sensors as per how tech ar trained to understand them etc, just tad better than some guy in a lockup on utube telling people he has done this and its fine, most things will be fine for a while how about after 20k running to hot and pinking dead engine coming soon,
hope this helps,
Today's computerized engine control systems rely on inputs from a variety of sensors to regulate engine performance, emissions and other important functions. The sensors must provide accurate information otherwise driveability problems, increased fuel consumption and emission failures can result.

One of the key sensors in this system is the oxygen sensor. It's often referred to as the "O2" sensor because O2 is the chemical formula for oxygen (oxygen atoms always travel in pairs, never alone).

The first O2 sensor was introduced in 1976 on a Volvo 240. California vehicles got them next in 1980 when California's emission rules required lower emissions. Federal emission laws made O2 sensors virtually mandatory on all cars and light trucks built since 1981. And now that OBD-II regulations are here (1996 and newer vehicles), many vehicles are now equipped with multiple O2 sensors, some as many as four!

The O2 sensor is mounted in the exhaust manifold to monitor how much unburned oxygen is in the exhaust as the exhaust exits the engine. Monitoring oxygen levels in the exhaust is a way of gauging the fuel mixture. It tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen).

A lot of factors can affect the relative richness or leanness of the fuel mixture, including air temperature, engine coolant temperature, barometric pressure, throttle position, air flow and engine load. There are other sensors to monitor these factors, too, but the O2 sensor is the master monitor for what's happening with the fuel mixture. Consequently, any problems with the O2 sensor can throw the whole system out of whack.

Loops
The computer uses the oxygen sensor's input to regulate the fuel mixture, which is referred to as the fuel "feedback control loop." The computer takes its cues from the O2 sensor and responds by changing the fuel mixture. This produces a corresponding change in the O2 sensor reading. This is referred to as "closed loop" operation because the computer is using the O2 sensor's input to regulate the fuel mixture. The result is a constant flip-flop back and forth from rich to lean which allows the catalytic converter to operate at peak efficiency while keeping the average overall fuel mixture in proper balance to minimize emissions. It's a complicated setup but it works.

When no signal is received from the O2 sensor, as is the case when a cold engine is first started (or the 02 sensor fails), the computer orders a fixed (unchanging) rich fuel mixture. This is referred to as "open loop" operation because no input is used from the O2 sensor to regulate the fuel mixture. If the engine fails to go into closed loop when the O2 sensor reaches operating temperature, or drops out of closed loop because the O2 sensor's signal is lost, the engine will run too rich causing an increase in fuel consumption and emissions. A bad coolant sensor can also prevent the system from going into closed loop because the computer also considers engine coolant temperature when deciding whether or not to go into closed loop.

How it Works
The O2 sensor works like a miniature generator and produces its own voltage when it gets hot. Inside the vented cover on the end of the sensor that screws into the exhaust manifold is a zirconium ceramic bulb. The bulb is coated on the outside with a porous layer of platinum. Inside the bulb are two strips of platinum that serve as electrodes or contacts.

The outside of the bulb is exposed to the hot gases in the exhaust while the inside of the bulb is vented internally through the sensor body to the outside atmosphere. Older style oxygen sensors actually have a small hole in the body shell so air can enter the sensor, but newer style O2 sensors "breathe" through their wire connectors and have no vent hole. It's hard to believe, but the tiny amount of space between the insulation and wire provides enough room for air to seep into the sensor (for this reason, grease should never be used on O2 sensor connectors because it can block the flow of air). Venting the sensor through the wires rather than with a hole in the body reduces the risk of dirt or water contamination that could foul the sensor from the inside and cause it to fail. The difference in oxygen levels between the exhaust and outside air within the sensor causes voltage to flow through the ceramic bulb. The greater the difference, the higher the voltage reading.

An oxygen sensor will typically generate up to about 0.9 volts when the fuel mixture is rich and there is little unburned oxygen in the exhaust. When the mixture is lean, the sensor's output voltage will drop down to about 0.1 volts. When the air/fuel mixture is balanced or at the equilibrium point of about 14.7 to 1, the sensor will read around 0.45 volts.

When the computer receives a rich signal (high voltage) from the O2 sensor, it leans the fuel mixture to reduce the sensor's reading. When the O2 sensor reading goes lean (low voltage), the computer reverses again making the fuel mixture go rich. This constant flip-flopping back and forth of the fuel mixture occurs with different speeds depending on the fuel system. The transition rate is slowest on engines with feedback carburetors, typically once per second at 2500 rpm. Engines with throttle body injection are somewhat faster (2 to 3 times per second at 2500 rpm), while engines with multiport injection are the fastest (5 to 7 times per second at 2500 rpm).

The oxygen sensor must be hot (about 600 degrees or higher) before it will start to generate a voltage signal, so many oxygen sensors have a small heating element inside to help them reach operating temperature more quickly. The heating element can also prevent the sensor from cooling off too much during prolonged idle, which would cause the system to revert to open loop.

Heated O2 sensors are used mostly in newer vehicles and typically have 3 or 4 wires. Older single wire O2 sensors do not have heaters. When replacing an O2 sensor, make sure it is the same type as the original (heated or unheated).

A New Role for O2 Sensors with OBDII
Starting with a few vehicles in 1994 and 1995, and all 1996 and newer vehicles, the number of oxygen sensors per engine has doubled. A second oxygen sensor is now used downstream of the catalytic converter to monitor the converter's operating efficiency. On V6 or V8 engines with dual exhausts, this means up to four O2 sensors (one for each cylinder bank and one after each converter) may be used.

The OBDII system is designed to monitor the emissions performance of the engine. This includes keeping an eye on anything that might cause emissions to increase. The OBDII system compares the oxygen level readings of the O2 sensors before and after the converter to see if the converter is reducing the pollutants in the exhaust. If it sees little or no change in oxygen level readings, it means the converter is not working properly. This will cause the Malfunction Indicator Lamp (MIL) to come on.

Sensor Diagnosis
O2 sensors are amazingly rugged considering the operating environment they live in. But O2 sensors do wear out and eventually have to be replaced. The performance of the O2 sensor tends to diminish with age as contaminants accumulate on the sensor tip and gradually reduce its ability to produce voltage. This kind of deterioration can be caused by a variety of substances that find their way into the exhaust such as lead, silicone, sulfur, oil ash and even some fuel additives. The sensor can also be damaged by environmental factors such as water, splash from road salt, oil and dirt.

As the sensor ages and becomes sluggish, the time it takes to react to changes in the air/fuel mixture slows down which causes emissions to go up. This happens because the flip-flopping of the fuel mixture is slowed down which reduces converter efficiency. The effect is more noticeable on engines with multiport fuel injection (MFI) than electronic carburetion or throttle body injection because the fuel ratio changes much more rapidly on MFI applications. If the sensor dies altogether, the result can be a fixed, rich fuel mixture. Default on most fuel injected applications is mid-range after three minutes. This causes a big jump in fuel consumption as well as emissions. And if the converter overheats because of the rich mixture, it may suffer damage. One EPA study found that 70% of the vehicles that failed an I/M 240 emissions test needed a new O2 sensor.

The only way to know if the O2 sensor is doing its job is to inspect it regularly. That's why some vehicles (mostly imports) have a sensor maintenance reminder light. A good time to check the sensor is when the spark plugs are changed.

You can read the O2 sensor's output with a scan tool or digital voltmeter, but the transitions are hard to see because the numbers jump around so much. Here's where a PC based scantool such as AutoTap really shines. You can use the graphing features to watch the transitions of the O2 sensors voltage. The software will display the sensor's voltage output as a wavy line that shows both it's amplitude (minimum and maximum voltage) as well as its frequency (transition rate from rich to lean).

A good O2 sensor should produce an oscillating waveform at idle that makes voltage transitions from near minimum (0.1 v) to near maximum (0.9v). Making the fuel mixture artificially rich by feeding propane into the intake manifold should cause the sensor to respond almost immediately (within 100 milliseconds) and go to maximum (0.9v) output. Creating a lean mixture by opening a vacuum line should cause the sensor's output to drop to its minimum (0.1v) value. If the sensor doesn't flip-flop back and forth quickly enough, it may indicate a need for replacement.

If the O2 sensor circuit opens, shorts or goes out of range, it may set a fault code and illuminate the Check Engine or Malfunction Indicator Lamp. If additional diagnosis reveals the sensor is defective, replacement is required. But many O2 sensors that are badly degraded continue to work well enough not to set a fault code-but not well enough to prevent an increase in emissions and fuel consumption. The absence of a fault code or warning lamp, therefore, does not mean the O2 sensor is functioning properly.

Sensor Replacement
Any O2 sensor that is defective obviously needs to be replaced. But there may also be benefits to replacing the O2 sensor periodically for preventive maintenance. Replacing an aging O2 sensor that has become sluggish can restore peak fuel efficiency, minimize exhaust emissions and prolong the life of the converter.

Unheated 1 or 2 wire wire O2 sensors on 1976 through early 1990s vehicles can be replaced every 30,000 to 50,000 miles. Heated 3 and 4-wire O2 sensors on mid-1980s through mid-1990s applications can be changed every 60,000 miles. On OBDII equipped vehicles (1996 & up), a replacement interval of 100,000 miles is recommended.
 

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Discussion Starter · #12 ·
So if I can't alter the wire were back at my main question .
What do I do about long tube headers then ? Is there a longer wired o2 sensors I can buy or a harness extender .?
Can someone with long tube headers chime in ?
I have 15 pulley and light weight crank,msd ignition ,headers, exhaust,intake,larger intercooler and a catch can
 

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So if I can't alter the wire were back at my main question .
What do I do about long tube headers then ? Is there a longer wired o2 sensors I can buy or a harness extender .?
Can someone with long tube headers chime in ?
I have 15 pulley and light weight crank,msd ignition ,headers, exhaust,intake,larger intercooler and a catch can
would that be a question to ask who sold the headers to you they must of designed it around what is there already wiring wise, if not then change the wiring on the car and not on the sensor its self, ie phone a breaker ask for the wiring lomb mainly the o2 sensor part and spice in sections to the wiring on the car to make it longer, this will ensure it all stays as per its meant to be for the ecu to play nice with it all.
 

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i have unpicked a wiring lomb before and found extra length from them, worth a punt
 

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Discussion Starter · #16 ·
After vast amounts of research and actually talking to an auto electrician I found that in order to extend an O2 sensor I must use copper wire such a speaker wire the correct gauge I can't use solder and I have to crimp it or twist I am together and people saying that the ohm resistance cuz of the heated wire blah blah blah add dates back to the old first versions of oxygen sensor where the lead wire contained in the oxygen sensor with the lead wire that actually ran through it for the element they don't make them like that anymore so I should be okay I'm going to install it and I'll let you guys know and I guess I can be the guinea pig for everybody else on this form when it comes to running long tube headers how to extend the oxygen sensor so if it works I'll do a little write-up Forum about it
 

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good luck
 

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Can I just ask what is the difference between extending the loom wiring or extending the oxegen sensor wire?
The resistance over such a small length will be irellevent, It's a very wide voltage swing of between 0.1 and .9 volts dc voltage from the sensor which is enormous in electronic terms. The current is tiny so I can't see it making any difference what so ever.
However saying that I would extend the loom just to keep the lambda sensors connector original.

Gerry
 

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Can I just ask what is the difference between extending the loom wiring or extending the oxegen sensor wire?
The resistance over such a small length will be irellevent, It's a very wide voltage swing of between 0.1 and .9 volts dc voltage from the sensor which is enormous in electronic terms. The current is tiny so I can't see it making any difference what so ever.
However saying that I would extend the loom just to keep the lambda sensors connector original.

Gerry
according to the bosch guy the sensor from its nozzle to its plug connector is design to work in a narrow resistance window, lower the voltage more smaller the resistances usd by the ecu.. ie its one of the lowest voltages on a car ie 0.9 to 0.1 volts, and when ecu switches to loop with upstream and down stream sensors they tend to sit around 0.45v the upstream one does most of the work and reacts more on a good system, so if you measure the volts on both sensors and both mimic the same volts thats a sign of cat melted away, same as if get upstream doing nothing compared with down stream indicates its faulty etc, dont take much to knock them out of spec, when you think 0.4v etherway will either over fuel on under fuel, the over fuel is very bad for the motor will cause over heating and melt piston rings etc, add that to a induced engine ie turbo super charged and its amplified greatly, then add a big remap and reduced pulley on super charged engines and its running 0.4v to rich trim is a lot for the pistons to handle no second chances,
ironically the mini engines dont like running with over fueling when added to timing chain stretching as well ie a retarded engine being force fed neat petrol gets down between the ring and ignities,,and the gen super charged ones tend to melt the head gasket between bores but will also melt piston crowns.
your right only way is to do the wiring lomb before the plug with the same wire, ie go breakers and snip a piece out of one to be sure, or like i said before as i would do count the strands of wires in the wires and match it like that,
 
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