Bank 1 sensor 2 is the downstream sensor. Heater control circuit fault 9/10 times shows a failing in the sensor, the other 1/10 it can be a wiring fault between the ecu and the sensor multi plug,or wiring between the multiplig and sensor itself.

We've seen very recently a faulty Maf sensor on a newly converted 140 car, fault was not present on 120i. The customer borrowed a sensor from a friend which fixed the fault, he then ordered a new sensor for himself, and the fault was still present which was hugely strange, more testing and another new maf sensor fitted and this cured the issue!! Faulty new sensor!!

Now a lot of us have covered more miles now more and more sensors are breaking down, I have a long list of customers with new MAF sensors, MAP sensors and O2 sensors!
A lot of people can be unwilling to accept that sensors can fail but we are tuning our cars and turning everything up so this is of course putting extra strain on everything which we have to accept!

So back to your fault Danny, maybe need to be testing the wiring fully back to the ecu, and testing the new sensor!!

 

A lot of people can be unwilling to accept that sensors can fail but we are tuning our cars and turning everything up so this is of course putting extra strain on everything which we have to accept!

especially sus/bush/train comps

 

Thanks buddy, great explainaiton too!

I will have to check the wiring...Shonky Ford

 

Will, how do we check the wires on the ECU side? Do you know which pins shall we check in the ECU connectors for the Bank1 sensor2 heater circuit and signal wires?
Can this be just a bad contact and by pulling the ECU connectors out and in again (with battery disconnected) may fix it?

CheeRS,
EO