So I needed to chase down an oil leak on my 2003 Z71 Tahoe with the 5.3 Flex engine...
I used some foaming degreaser and a hose and was able to isolate the oil leak...
unfortunately I got a little too overzealous with the hose because the next day I get a knock sensor code...
apparently I got some water in the valley and flooded one of my knock sensors... no big deal... the Tahoe has 170k on the clock and I have been meaning to replace the intake manifold gasket anyway...
so I get the parts, watch a few dozen YouTube videos and go at it... everything came a part and went back together without too much difficulty...
I cleared the codes and drove around and the knock sensor code did NOT come back... I think success!
That was until the next day... my wife drove the Tahoe to work and texted me that the check engine light had come back on... when I got home I plugged in the scanner and I had a P0178 code (fuel composition sensor circuit low input)
after some research I removed and replaced the sensor, cleaned the connector plug and replaced the fuel filter... I cleared the codes and the P0178 code came right back...
I took the sensor back and replaced it a second time... same deal... after clearing the codes the P0178 code came right back.
I did a little more research in order to test the voltage to the plug... there are 3 wires A, B & C
The A wire is a signal wire that is supposed to carry 5v, the B wire is a power wire that is supposed to carry 12v and the C wire is ground.
When I tested the A wire it read 11.2v with the motor off and 13.2v running, the B wire read 13.3v with the motor off and 14.2 running...
I suspected that maybe the A& B wires somewhere between the sensor plug and the PCM so I pulled the PCM fuses and did a continuity check between the A &B wires and they tested as an open circuit so I don't believe that they are shorted to one another...
I'm kind of at a loss now and don't know what to check next.
Any input would be greatly appreciated
I used some foaming degreaser and a hose and was able to isolate the oil leak...
unfortunately I got a little too overzealous with the hose because the next day I get a knock sensor code...
apparently I got some water in the valley and flooded one of my knock sensors... no big deal... the Tahoe has 170k on the clock and I have been meaning to replace the intake manifold gasket anyway...
so I get the parts, watch a few dozen YouTube videos and go at it... everything came a part and went back together without too much difficulty...
I cleared the codes and drove around and the knock sensor code did NOT come back... I think success!
That was until the next day... my wife drove the Tahoe to work and texted me that the check engine light had come back on... when I got home I plugged in the scanner and I had a P0178 code (fuel composition sensor circuit low input)
after some research I removed and replaced the sensor, cleaned the connector plug and replaced the fuel filter... I cleared the codes and the P0178 code came right back...
I took the sensor back and replaced it a second time... same deal... after clearing the codes the P0178 code came right back.
I did a little more research in order to test the voltage to the plug... there are 3 wires A, B & C
The A wire is a signal wire that is supposed to carry 5v, the B wire is a power wire that is supposed to carry 12v and the C wire is ground.
When I tested the A wire it read 11.2v with the motor off and 13.2v running, the B wire read 13.3v with the motor off and 14.2 running...
I suspected that maybe the A& B wires somewhere between the sensor plug and the PCM so I pulled the PCM fuses and did a continuity check between the A &B wires and they tested as an open circuit so I don't believe that they are shorted to one another...
I'm kind of at a loss now and don't know what to check next.
Any input would be greatly appreciated
