Error code 8d oxygen sensor control P0170

[PRB]

Evening,

The engine management light is on on my 2001 1.9 Z3. I can reset it, but about 20miles later it returns! (Image from code reader attached).

As I understand it, the fault could be;
- damaged pipework (all seems intact)
- MAF sensor
- Pre catalyst oxygen sensor
- Post catalyst oxygen sensor

Anyone any suggestions as to how to go about diagnosing the correct fault? Is there more information in the fault code that I'm not understanding that will help to identify it?

Many thanks, Paul

 

[Stevo7682]

Most likely an air leak that would be first thing to check
Stephen.

 

[PRB]

Thanks, any particular points that are known to commonly leak?

 

[Stevo7682]

Air intake pipe

 

[colb]

If you cant find any air leaks by visual check a smoke test should pinpoint where they are if there are any. Also if you can view live data with diagnostics a look at your fuel trims would indicate if you do have air leaks, if the trims are high it is an indication that the car thinks its running lean and will be adding fuel, it may well be that your exhaust sensors are picking up this extra fuel and is reporting its reached the max level. Don't fall into the trap of thinking because a sensor reports a fault it has gone bad, the cause may well be futher back from the sensor reporting the error. Maf sensors don't always set fault codes, and cleaning them is in my experience hit and miss. When I had a bad Maf I replaced with oem part, tried a cheap ebay one but that didn't work. Some do report success using the cheap Mafs but you run the risk of paying twice if the cheap versions don't solve your problems.

 

[PRB]

Thanks, more investigation work needed then!