This is at my job where even the experienced mechanics are stumped..

05 TSX with a k24 comes in with a CEL. P2195 (o2 stuck lean) and a p0171 (system too lean).

I'm looking at the system with a snap on scanner and see

AFR 14.56
LTFT 19%
STFT 0%
HO2S1 0
HO2S1 HTR OFF

and the downstream sensor occasionally gets a reading but most of the time is dead and the car has definitely ran long enough for closed loop.

I tested the oxygen sensor disconnected from the harness. I get microvolt readings that vary with the engine rpm. The o2 sensor seems to be working perfectly.

But at the harness I'm getting no voltage or ground at the heater and the volts specified by the snap on for the sensor wires are out of spec.

Seems like a bad ECU or harness. But that's rare...

The other mechanic tried clearing the codes and every time they popped up 10 seconds after the car is restarted.

So anyone know if there is a common issue with the tsx/k24s?

And would the downstream sensor stop reading if the ECU sees that the upstream is bad?


Thanks

 

i would start with an exhaust leak test using seafoam and look for white smoke leaking out

 

Probably the only good application of Seafoam I've ever heard of.

 

Thanks for the suggestion but I could not find one. The o2 sensor reads absolutely nothing at the ECU, even though its fully functioning. The computer would still show something even if there was an exhaust leak.

 

lol totally agreed xD

 

lean = too much oxygen