Oxygen sensor code 4-3-6?

iankleinfeld · Post by **iankleinfeld** » 28 Feb 2005, 06:05

Still trying to figure this one out... Havnen't gotten any replies yet.

I recently had the check engine light go on, got code 4-3-6, which is Rear heated oxygen sensor compensation. OK, now what is that? I know what a rear O2 sensor is but what is compensation and how do I fix it? Can't find anything anywhere about this. Should I just replace the O2 sensor?

Post by **dosbricks** » 28 Feb 2005, 08:28

From volvospeed.com:
"EFI-436; the ECM monitors the compensation being made by the rear sensor and sets this code when excessive compensation (between the two sensors) is being called for. Note: the front sensor can cause this code to be set in the rear."

How many miles on these sensors? Usually the front one wears out first (becomes slow to respond) because it is closer to the combustion heat. If they are original and have 80-100k on them, they propably have about had the course.

TOMMY · Post by **TOMMY** » 05 Jun 2006, 15:28

I pulled the 4-3-6 code today and reset the ecu. Im going to drive it a bit to see if the code comes back before I start buying parts...just wondering...where when i find a source for all or most of the codes for a 95 850

Post by **MadeInJapan** » 05 Jun 2006, 22:21

Here ya go:
http://au.geocities.com/ozbrick850/comp ... volvo.html

TOMMY · Post by **TOMMY** » 05 Jun 2006, 23:56

perfect thanks

TOMMY · Post by **TOMMY** » 05 Jul 2006, 09:26

Hi everyone,

I'm a newb with this car. This is my first time repairing the front 02 sensor on my car (before cat) and when I went to change it, I saw that there are 2 sets of cables leaving the sensor. One is the normal one which is wired up to where the other 02 sensor is connected, and the other cable is going somewhere under my battery (I cant really see where it goes bc its hidden but thats the general area). Anyone have a clue what this other cable is?