It was very disheartening after spending $263 CDN on an Volvo front O2 sensor and after replacing it, not being able to clear the codes.

Has anyone ever come across this? I keep reading and reading the codes and all that is there is 435 - both before and after replacement. I drove it for a bit, and read again and the same thing. The performance of the car isn't quite what I think it should be (854T) and I am hoping that teh ECU is being conservative because of the codes. Any help would be great. BTW - I am using the instructions from Bay 13 as to how to read and reset codes.

Thanks in advance
Stephen

1994 854T, 1988 745T

Another way to do it is like this.

disconnected the battery over ninght... this way the ECU will forget every thing when you reconnected it again....

said you should disconnect it at least 6 hours before this work... this will clear all the code and memory in the ECU...
yes 94 do have problem with it ECU///

Thanks for the suggestion. I had to go on a road trip this afternoon and when I got back I tried a few more times. Finally it took and the code reset. My Lambda light went off for the first time in 2 months - woohoo!!

So just a quick question. I want to confirm that you are saying - there is a problem with a 94 ECU where codes are troublesome to reset and the best way to deal with it is to disconnect the battery overnight? If this is the case, thanks for the advice. I will remember this for next time for sure.

Thanks
Stephen

Are you able to reset the code? Can you make the "check engine" light go out?

Here's the procedure from the IPD catalog. (You have to view all the codes at least once before resetting.)

Ignition on, test lead in socket A2.
Press the button for at least 5 seconds and wait for at least 3 seconds.
The LED will blink rapidly. (Actually, mine just comes on steady at this point)
While it's blinking (or in my case, ON) Press the button for at least 5 seconds and release.
The LED will go out.
Turn off the ignition.
Turn on the ignition and check codes. Should just be the 1-1-1. (No Codes)
If there are any, read and clear them, then attempt the reset again.
Turn ignition off, remove jumper from A2 and start car. Should be no CE light.

If you are sucessfull in resetting and your CE comes back on shortly thereafter with an 02 code, check for vacumn leaks at the elbows mentioned on Bay 13.

Good luck
--
Erwin in Memphis, '95855t, '86 Guzzi LeMans, '76 Montesa 348 Cota