93 190e 2.3 Airflow sensor rebuildable ????? - PeachParts Mercedes-Benz Forum

smk_texas · #1 08-25-2006, 01:09 PM

The CEL is on in my 93 190e 2.3 4cyl. Diagnosis returned code 4 - airflow sensor position indicator. I installed a new pot (the existing pot was just fine without any wear)& adjusted to specs but CEL won't go away.

Is the airflow sensor repairable ??? or should I buy a new one ???? Also, is it possible for some other fault to trigger a code 4 ???? Please help.

Thanks
smk_texas
98 s420
93 190e 2.4

david s poole · #2 08-25-2006, 01:45 PM

what are you calling the airflow position sender? my understanding is that it is part of the upper plenum,just below the fuel distributor and cannot be purchased separately.besides requires equipment and expertise to set up properly. david poole dallas tx. 214-9567007.

smk_texas · #3 08-25-2006, 02:32 PM

David,

Here is a picture of the sensor on my car. You are not saying that I should also buy the fuel distributor, are you ???? Thanks.

mctwin2kman · #4 08-25-2006, 03:50 PM

Quote:

Originally Posted by david s poole

what are you calling the airflow position sender? my understanding is that it is part of the upper plenum,just below the fuel distributor and cannot be purchased separately.besides requires equipment and expertise to set up properly. david poole dallas tx. 214-9567007.

You can buy them and set them up properly. Not hard really as I did it a few months ago. All you need it the proper Bosch Part number. And to know how to set it up. There is a procedure on this very forum of how to do it and where to get it.

OP, are you sure a wire is not bad out of the three on it? Check the wiring and ensure that there is not a broken one. And what procedure did you use to set the new one? Mine was visibly worn, and when I put the new on it I noticed the little pins on the sweep arm were not contacting the new on and needed a little adjustment to have proper contact with the new sensor. Had to take it off three times before I could get everything perfect. Only pain is the FPR having to be removed to get the darn screws all out and the lose of fuel pressure making the plate drop so you need to hook all back up and turn key on to test. Just was time consuming.

smk_texas · #5 08-25-2006, 05:24 PM

I'll search for the replacement procedure here. In case you find it please post. You had mentioned the 3 wires....is it visible when I remove the airfilter housing ??? Is it the plug with 3 wires that plugs into the POT ???

Now, on the AFM POT procedure:
I found the procedure on this forum by Steve Brotherton & sbourg. I removed the old one and was surprised to find that it had very little wear on it. Since I already bought the new one, I went ahead and put it in. I basically marked a line around the exsiting one and installed the new one within that line. I had to move a tad bit CCW to achieve .7v on pin 2 with pin3 grounded. I agree with you....it was messy unplugging the FPR with fuel leaking all around. I did unscrew the gas cap and stuck a screw driver to keep that lid open which I think helped minimise the fuel leak.

The new POT did not seem to help. The erractic idle is still there. The CEL is still ON (after reset) with code# 4. If the 3 wires you mentioned look good, then I am looking at AFM replacement most probably. Thanks for your help.

smk_texas
98 s420
93 190e

david s poole · #6 08-25-2006, 05:29 PM

no i'm not saying you should buy the fuel distributor as well for it seems as though you have correct part.from what i remember the check eng light was mostly brought on by o2 sensor in those cars. have you checked the plugs and wiring?

smk_texas · #7 08-25-2006, 05:49 PM

I haven't checked the O2 sensor. The plugs & wires are good. I'll test the o2 sensor this weekend. Will a bad O2 sensor trigger a code 4 ???? I thought the code for o2 sensor was 5. Please advise. Thanks