What's triggering check engine light?

[velorossa22]

I wanted to start a thread for everyone about CEL lights ( check engine). Maybe we can all compare notes on what triggers the car to go to open loop mode. Like has anyone experienced a problem with o2 sensor extenders, or O2 EFIE or even MAP enhancers? If so what was the code associated with them. I'm hoping if we share the codes we can know what caused what. For instance my subaru's light came on today with the generator at 20A. Code was PO 0420 bank 1 below threshold. Thinking maybe o2 sensor issue. I don't think though it was b/c of the generator since I've seen this in go on before w/o the generator.
I can prevent the light from coming on in my suburban. It will always go on when I'm on the freeway except when the generator is running. Kinda funny huh?

[Painless]

The only issues I've had on my dodge ram with going into open loop were when signal from the O2 sensors was lost or enhanced too much.

[velorossa22]

So you never seen it going into open loop mode when it just had o2 sensor extenders? When it was triggered do you remember what OBD code it sent to you?

[Painless]

I can't remember the specific code, it was something to do with 'Cannot enter closed loop fuel control'.

I suppose extenders might be able to cause issues, if they pulled the sensor too far out of the stream.

[velorossa22]

Got a new CEL light, need to get it read. THe car has a idle bouncing up and down issue. I'll let you know what it says.
DON"T LET KOH LEAK ONTO YOUR CAR ELECTRICALS!!!!!!!!!!!!!
I'm suspecting that may be the cause of my issue.

[bigjim56]

I've only gotten a CEL from using the map sensor. I've recently installed an EFIE and have ramped it to 100 % w/no CEL tripping. Using the map sensor sets it off rather easily if the idle gets too low.

bigjim56

[velorossa22]

So I think I fixed it. The car seems happy now. Gave me po505 engine code, which is traced to idle ( often IAC). I took the IAC off and inspected it, and it looked okay, but when I put it back on the car seemed happy about it. This problem started when my cell went to ground and started tripping the circuit breaker, but this breaker lets fault current go for longer than I'm comfortable with. It turned itself off and on a few times and that's when the idle got messed up. So maybe the current/ voltage spikes set my IAC into a tizzy since it is controlled by an electromagnet. I pulled it off and reseated and hopefully I will be good to go ( car didn't set CEL immediately like it was doing)...

[velorossa22]

Word of warning! For some reason my cell was creating throttle issues. I don't know why exactly but after leaving the cell off for a week the car seemed to return back to normal, but when I started to run the cell again the problems returned. Let me know if you guys know what's causing the issue. I feel like somehow KOH is getting vaporized and into the TB.