P0138 MIL code.

[TheForce]

Today I remove the EGR valve to test it and to see if the port may have been clogged. I cleaned the plate and valve last year but I'm still having the bucking problem. Anyway I tested the valve and it all works.

When I replaced the valve I connected the wire harness and I took the car for a spin. After a driving a while I got a P0138 code. Which is "P0138 Secondary Heated Oxygen Sensor (Secondary HO2S) Circuit High Voltage". Not being a car guy what sensor do I need to replace? Or do I need to replace it?




Just a side note that a while back I did have the EGR valve unplugged and the bucking stopped. Do I need to replace the EGR valve too even though I think it tested good? Or is the oxygen sensor the cause of the bucking now?

[Eli]

O2 sensor will not cause bucking. The EGR valve "working" doesn't mean it's actually working. The reason for the bucking is that the carbon track inside gets worn.

You can try drilling a hole in it and spraying it with contact cleaner, people have had good success with that. I'd probably just replace it though, there's nothing like the feeling of a new EGR valve.

The code means your secondary O2 sensor has failed.

[TheForce]

When I had the valve apart last year the carbon tracks looked new and not worn down at all. I could not even see a worn track in the carbon. Does it still sound like I need to replace the valve?

Which sensor will I need to buy? Have a part number?

[TheForce]

Will the bosch o2 sensors work with the Insight? Anyone have the correct part numbers?

[TheForce]

I did not want to leave this post unanswered.

Lean burn is now working great now since I replaced both sensors. I think just the secondary needed replaced but I replaced both just in case.