O2 Sensor Heater - Wiring Loom?

[gdlow]

Hi,

A while ago my 2001 K11 was throwing Lean errors and Heater Sensor errors. It was running really rich which suggested a busted O2 sensor. It had done 90,000 miles so that was about right. New O2 sensor (proper Bosch one) sorted it - goes really well now.

But it still throws Heater Sensor errors. And they are becoming more regular, infact the MIL is rarely off now.

Resistance over the heater is just over 7 ohms which I guess is right?

So I started checking the loom. I've tried all sorts of tests from the ECU harness to the point where the O2 sensor connects. But without a wiring diagram I am guessing a lot. So I got a couple of questions:

• which pins am I looking for and how do I identify them (Haynes doesn't show the ECU harness or O2 sensors for the newer K11s, only the older ones
• is it a straight wire run from the ECU to the O2 Sensor plug - no resistors or relays?

Any pointers much appreciated!
Thanks, Gaz.

 

[frank]

the russian or polish pdf manual has the wiring diags for the coilpack engines iirc gaz, and you should have 2 lambda,s ?

 

[gdlow]

Hi. Yeah - there are two O2s. There are two O2's - it could be the other one! Never occurred to me! Been looking at a Russian manual, but really struggling to make any headway with it. My ECU has three rows of pins - the ones on the Russian manual only have two, but it says it goes up to 2002.

 

[gdlow]

I measured the current and resistance of both O2s. Does this sound reasonable:
front (1st sensor): 7.0 Ohms and 1.5 Amps dropping to 0.8 after 20 secs
rear (2nd sensor): 5.4 Ohms and 2.5 Amps dropping to 1.3 after 20 secs.

Should they be that different?

Cheers, Gaz.