Got a 1221 code after stomp test, need direction

[pismojeff]

I just did a stomp test on my 93 525it after I had a CEL go on yesterday. I know that the code is for the O2 sensor, but is that what I should immediately replace or could it be a host of other problems. I am new to this and would like any experience that you guys could share. It had the surging problem before the CEL went on and then immediately after the CEL went on the surging went away. Please help. I am ready to replace the O2 sensor, but didn't want to jump the gun. Thanks,

Jeff

[ryan roopnarine]

I just did a stomp test on my 93 525it after I had a CEL go on yesterday. I know that the code is for the O2 sensor, but is that what I should immediately replace or could it be a host of other problems. I am new to this and would like any experience that you guys could share. It had the surging problem before the CEL went on and then immediately after the CEL went on the surging went away. Please help. I am ready to replace the O2 sensor, but didn't want to jump the gun. Thanks,

Jeff

i think that once your CEL goes on, the car disregards the o2 sensor if it is indeed the o2 sensor that is defective. i find that after i decarbonize effectively with in tank cleaners, the car surges because a bit because of the carbon that ends up on the o2 sensor. id wonder if your mechanic did something at the last minute to help your car pass emissions that dumped a bit of the carbon onto it. i find that mine cleans with a couple of passes in 2nd gear at 60 mph (around 5700 rpm) for 1.5 minutes, followed by a couple in 3rd at 70, repeat. it was probably due for replacement anyway, but the 1221 definately DOES NOT mean that it is indeed the 02 sensor that needs replacement (i've had several air leaks and air restrictions do the same thing). has your gas mileage gone down since the CEL came on as compared to when it was surging?

[pismojeff]

Ok, I did the passes like you said in second and third. Now what do I do? Do I try to clear the check engine light. How do I do that? I haven't noticed a big drop off in gas mileage since the light went on, but it hasn't really been long enough for me to tell. I will keep an eye on that. I have replaced a few air hoses as well as this was the first place that was recommended that I start. Thanks for the help!

[pismojeff]

Anyone else have more insight on this? Please help!

[632 Regal]

can also cause an O2 code just to mess with you.