Hi guys,

 

I have a 2007 octavia VRS 2.0 TFSI BWA engine.

 

I managed to smash off the post lambda sensor after mounting the decat pipe with the lambda point down towards the road ! ( silly ... school boy error ) This was only after it was on for a bout 6 weeks where all was well up to that point

 

After that I had P0139 and P0140 errors .. sensor 1 bank 2 slow response etc.  I replaced the sensor with a £90 one from euro, no good. bought a £20 from ebay ... no good ... so I got a genuine one from volkswagan at £152 !!    ... still no good !  - meaning I get error still and VCDS doesnt show the sensor or resistance at all

 

From the connector on the car side I am getting 11 volts for the heater and 0.45v for the sensor, that appears to be in range. I have checked the sensor and I have 9 Ohms for the heater that appears to be good. The sensor side of the lambdaI seem to get open curcuit ... but I assume that is because the lambda wasnt plugged in whenm I tested it

 

I have also tested the voltage when plugged in and can confirm the heater is getting 11 volts.  ( So I think I can cancel out a dodgy connector and Im sure a genuine sensor is good too )

 

So Now I am left with wiring going back to the ECU or the ECU itself.

 

My best guess is I have shorted out the wiring when I smashed off the sensor and possibly the heater wires has touched the sensor wires. and blown a track off the ECU.

 

But I need to test the wiring to the ECU first before I venchure down that route.

 

 Does anyone know the pin outs for the Post lambda sensor on the ECU please. ...???

 

 

Many thanks

 

 

It should be like this:;

Sensor connector pin 1 - white/red - from fuse 12 (heater supply 12V)

Sensor connector pin 2 - brown/green - to ECU pin 7 (heater modulation)

Sensor connector pin 3 - black - to ECU pin 76

Sensor connector pin 4 - blue - to ECU pin 77

Thanks very much

 thats great

No problem.

If you haven't already done so, you should change the angle of the sensor so that its tip is lower than its wire entry point, if you see what I mean.

This is so that any condensation runs downward, away from the innards of the sensor, rather than towards.  Not sure how essential this is, but when I mounted a DIY sensor on a previous car without meeting this condition, one or two 'internauts' tutted and sucked their teeth and said it would soon die. It kept going for at least a couple or three years 'til I sold the car though.