Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I came across this issue twice on vw and volvo, and this two fault is happening to same
Sensor. O2 sensor, 4 wires. I notice that the earth or ground wire flashes or blinks, , for Volvo new oxygen was change yet still issue persist, same as the VW mk6, on the Volvo a used pcm was replaced to the original pcm, yet the problem still persist, and this issue ignite check light telling that the sensor is not working whereas they are new ans there is no short to ground or earth if you do continuity test on the line alone. What is common about this two cars is that, the get their earth from the pcm, power from fuse box, Yet this two cars ground blinks and complain that the sensor is not good. Even though sensors are oem, please need help as to whosoever has face this issue before. And how it was dealt with.
Thank
Christ De Way Maker
The following user(s) said Thank You: aboudi.naddaf
Yes, it sparking , whenever the car is started , and you put test light to the earth wire that come from the pcm, you see it sparking, but when you ground or earth the tester to the car body and you check the positive side of the wire that comes from fuse side, no spark, so I am wondering why the ground or earth from
the board should be giving such flashing light or sparking light...
Christ De Way Maker
The following user(s) said Thank You: Desmond6004, aboudi.naddaf
You may be seeing the pulse controlled heater ground on this 4 wire sensor:
There is a constant voltage feed to the O2 sensor heater circuit and this circuit ispulse controlled to ground by the ecm. When it is pulsed to ground there's no voltage on the control wire and your test light will not light. When it is not pulsed to ground then there will be open circuit voltage on the ground wire and your test light will light.
The heater wires are often times the same color helping to identify them....
To verify proper O2 sensor function check the signal wire with a scope or a multimeter .
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
The following user(s) said Thank You: Noah, Desmond6004, aboudi.naddaf
Topic Author
