Check Engine light comes and goes....

[JamesM3M5]

From the first day that I drove my new-to-me 95 M3, the CEL will come and go. It usually does it when I accelerate in 1st or 2nd and hang around 3-4k RPMs for a bit before shifting.

It runs exceptionally well, even when the CEL is going on and off. The car failed emissions right before I bought it, but it passed the next time around. It probably received a new O2 sensor.

I tried reading the fault codes, but after I press the gas pedal 5 times, the CEL simply stays on and never blinks. Shouldn't it at least blink 1-4-4-4 to show all clear? Or not? Car was built 7/95.

Thanks!

[RogRacer]

10-1 odds the flashing CE light is a knock sensor code. You need to pull the code to check for sure......I forget the "tap the pedal" procedure...I use a Peake reader...but it's in the Bently manual and Conforti's web site, IIRC. It's a little tricky with the timing of the taps, but I'm sure you can do it if you play around a little

[JamesM3M5]

Hmm, odd, I don't feel the engine retarding the timing, but it may be running a tad lean. I think it's all stock, haven't checked for the presence of an aftermarket chip. When running it hard, it doesn't act like it has to retard timing, either. Only when I accelerate gently in 1, 2, or 3 and hold the revs around 3-4k will the CEL come on. As soon as I'm out of that rev range, the light goes off.

I tried for 5 mins to get the CEL to blink the codes at me. The Bentley says just hit it 5 times in 5 seconds. I did 5 times moderately fast, 5 times medium, 5 times slow, but nothing.

[AvusMPower]

Check www.bonnevillemotorwerks.com's tech tips. That worked for me.

[GQ_Style]

I agree with RogRacer, proabably your #1 knock sensor. Your fault code should blink 1221. Pretty common with the 95 M3's.

[JamesM3M5]

Originally posted by RogRacer
10-1 odds the flashing CE light is a knock sensor code. You need to pull the code to check for sure......I forget the "tap the pedal" procedure...I use a Peake reader...but it's in the Bently manual and Conforti's web site, IIRC. It's a little tricky with the timing of the taps, but I'm sure you can do it if you play around a little

Ding Ding Ding!! You win the grand prize.

I FINALLY got the damn CEL to flash the code:1226

Since you have to remove the intake manifold to do the stupid job, I'm gonna go ahead and replace both.

Thanks for the help, guys.

[ImageDynamicsM3]

It comes on somtimes when I do wicked clutch drops on the shitty AZ gas... gotta love schrick cams and 91 LOL

[RogRacer]

Originally posted by JamesM3M5
Ding Ding Ding!! You win the grand prize.

I FINALLY got the damn CEL to flash the code:1226

Since you have to remove the intake manifold to do the stupid job, I'm gonna go ahead and replace both.

Thanks for the help, guys.

Before you go to the trouble of replacing the sensors, I suggest you re-torque (or replace) the spark plugs and clean the electrical connector at the DME with elec contact cleaner. These things have been reported to silence the knock sensor code on occassion......

[JamesM3M5]

I have new plugs waiting for me at home. I'll also try cleaning the contacts. I have some good spray contact cleaner for problems just like this. If that doesn't cure it, I guess I have my work cut out for me.

Thanks for the help!!

[DravisAR]

Not to bring this one back from the dead on purpose...but how did you pull the code? my brand new (to me) 4/95 is throwing a code....and I dont have a reader. The 5 taps in 5 seconds didnt work for me, and bonneville's site is down.

Thanks!

Alex

[Balthazarr]

Hold the last tap down if you haven't already.

[DravisAR]

Thats all it took....1221 Oxygen Sensor #1...any idea on replacement cost/time? Id think it would be easy...

Lift car...unscrew old, screw in new, done!

[Balthazarr]

I bought one months ago just in case, but what i've found is that
you have to either use the special slotted socket with offset for drive wrench or an open ender.
It depends on how much clearance you have.
It's pretty tight down there.

[John H]

Yeah, you need a special tool, but you can buy a full o2 sensor set (with several sizes) at most auto stores for ~$20 or so.

you could also try cleaning the sensor, but with that kind of mileage, i would just replace it. forget what the cost of the part is. more than $10, less than $100.

Glad to hear it's nothing serious (not to say it's not important!).

- John

[DravisAR]

So will that bad O2 sensor cause any issues other than the car running a little rich? I need to have it replaced obviously, calling the dealer on that today (the used car dealer said they would have it fixed for me)

The cars been driven hard alot lately with the bad sensor, so just wondering if this could cause any serious issues.

Thanks again guys!

Alex

[Ron17]

New O2 Sensor

[rdbwong]

My CEL just came up recently and the code came out to be #1221. Is the car still driveable till I get it fixed. Sorry if it sounds like a dumb question. I'm a newb. Thanks.

[Ron17]

Originally posted by rdbwong
My CEL just came up recently and the code came out to be #1221. Is the car still driveable till I get it fixed. Sorry if it sounds like a dumb question. I'm a newb. Thanks.

That's EGO Sensor #1. I can't remember exactly what that does, though. Perhaps someone else knows.