Limp mode AFTER clearing CEL
 

So I was driving around with a CEL for a couple of weeks.

I hooked up an OBD and found it was a P0420, which I then cleared, as I had this same issue around 12 months ago (I had the dealer replace the 02 sensor).

Immediately after I cleared it, I found the car became extremely sluggish at low revs, almost limp (it was fine when the CEL was on!).

For the record, I have the SpeedFactory UEL catted headers with a custom ECUTEK tune.

Thoughts?

I have the same header and tune . I get the same CEL and traction light out of the blue I've taken it back to the tuner a couple of times now and the codes clear themselves after a couple of start and shutdown of car.

With some CELs the car will be sluggish for a while after clearing until the ECU has gone through several start cycles. Just drive it for a few days and see if the power doesn't come back.

I had a CEL for a comm issue that put the car into limp mode. When I cleared it, it was sluggish as an arthritic hound in August. I thought I had done some kind of permanent damage. But two days later it was screaming again.

Just another weird normal thing about these cars.

re-learning process...

You sir are a far braver soul than I!. I get a CEL I am pulling the code within hours not weeks.

Drive for 200 miles easy so it relearns.

My air/fuel was off, and I kept stalling over and over until I drove my FRS approx 200 miles after installing the TRD intake. I unplugged battery for about 6hrs while I worked on it, so yeah.

Just take it slow for 200miles.

Oh and when I did my fog lights, same thing! I stalled for two days until I reached 200 miles.

Even catted headers will not guarantee ecu will not throw P0420 cat efficiency cel code as the ecu is looking for the readings of the stock cat, if the aftermarket cat does not give same reading it will trigger cel.


Get your tuner to disable P0420 in tune.


When you reset CEL codes you reset ECU, learned parameters like fuel trims, throttle initial calibration are cleared, you will likely get the "dead" feeling throttle for first couple of drive cycles.


Cycle the ignition 2 or three times 30 sec intervals without touching the throttle.


Then do 2 or 3 very light throttle runs from 2000-5000 rpm 2nd gear should be sorted.


have a read of the Flashing Reset Learning link below

Great info, thanks so much!

Given that I'm getting the CEL even with the cat, I'm strongly considering either punching it out or getting some catless headers. Would this require a retune?

yes will require tune adjustment, probably not the best to just knock the cat out , you would need to cut it out and weld in a piecie of pipe else it wont flow well.

or sell them and buy catless version