oxygen sensors
#1
04-14-2017, 05:02 PM
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oxygen sensors
I have a 2.0 T5 (226 HP, 1999) engine problem: the color of the spark plugs is white, as the front and back oxygen sensors and the turbo. This means the car gets less petrol. I can also hear that the ignition rings.
I thought first it has an oxygen sensor problem but after checking it with a diagnostic computer, the computer showed a cut in the circuit. I tried the back oxygen sensors in an other C70 as the jack is the same in both cars. It worked and was communicating with the computer.
I do not know the front oxygen sensor having in T5, it is not a common 4-cable one but it is with a 6-leg jack.
Question: the problem with the front oxygen sensor can cause the communication problem with the back one? Any other experiences on why the car is not communicating with the oxygen sensors? Do you have any other ideas on receiving less petrol if the injection is OK?
Add info: ckeck engine light is not on, during a basic problem checking the problem is not stored, the problem related to the oxygen sensor can be seen only when I list the parameters.
Thanks a lot!
Yvette
I thought first it has an oxygen sensor problem but after checking it with a diagnostic computer, the computer showed a cut in the circuit. I tried the back oxygen sensors in an other C70 as the jack is the same in both cars. It worked and was communicating with the computer.
I do not know the front oxygen sensor having in T5, it is not a common 4-cable one but it is with a 6-leg jack.
Question: the problem with the front oxygen sensor can cause the communication problem with the back one? Any other experiences on why the car is not communicating with the oxygen sensors? Do you have any other ideas on receiving less petrol if the injection is OK?
Add info: ckeck engine light is not on, during a basic problem checking the problem is not stored, the problem related to the oxygen sensor can be seen only when I list the parameters.
Thanks a lot!
Yvette
#2
04-17-2017, 01:38 PM
the front sensor is used to control the mixture, the rear is post cat and the ECU measure the different between the two to determine the catalytic converter's efficiency. Your car can run just fine without the rear sensor - but you'd get a P0420 code (catalytic threshold error).
What is going on that you think you have a problem? If your car were running lean, then the front O2 sensor would go out of range (ie can't compensate) and you'd get a CEL. If you unplug the sensor do you get a CEL?
If you have an OBD2 reader that can pull real time data there are some tests you can run to see if the sensors are actuating (say by pulling a vacuum line or spraying in some carb or maf cleaning while the engine is running to see if that moves the readings).
Thinking about what can cause a lean mixture - air/vacuum leaks are most common. you could have a fuel pressure issue so you'd need to put a gauge on the fuel rail. the MAF and idle air valve could be dirty but normally those present rough idles, start issues
Last thought is maybe you have the wrong plugs. Try going back to OEM standard part number and make sure the gap is correct per the owners manual.
What is going on that you think you have a problem? If your car were running lean, then the front O2 sensor would go out of range (ie can't compensate) and you'd get a CEL. If you unplug the sensor do you get a CEL?
If you have an OBD2 reader that can pull real time data there are some tests you can run to see if the sensors are actuating (say by pulling a vacuum line or spraying in some carb or maf cleaning while the engine is running to see if that moves the readings).
Thinking about what can cause a lean mixture - air/vacuum leaks are most common. you could have a fuel pressure issue so you'd need to put a gauge on the fuel rail. the MAF and idle air valve could be dirty but normally those present rough idles, start issues
Last thought is maybe you have the wrong plugs. Try going back to OEM standard part number and make sure the gap is correct per the owners manual.
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