[Biturbos4] Coolant sensor

[Quincy Chiang]

Hi everyone,

I got a CEL last friday night when it was -25 oC outside, it stayed on all Saturday but cleared itself yesterday.  I figured I'd be safe and drop by the dealer at lunch today.  I was expecting a MAF or a torn TBB, but it tuned out to be a coolant sensor, it's out of spec by up to 10 oC.

I did a quick search on the AW S4 archive, apparently this sensor is known to fail, quite frequently I might add.  It can cause rich or lean conditions, cold start and idle problems, erractic coolant temp gauge and other issues.  Also the original sensor (black) has been superceded by a newer version (green).   I learn something new everyday, just thought I'd share my findings.

Btw, happy new year!!

Quincy
'01.5 S4
'90 CQ