Lambda Sensors

[n_mistry]

Afternoon folks, I'm getting the check engine light, drives fine so figured its the O2 sensors. This was the case when I used to own an E46 330Ci. Same engine as my Z3 3.0 so guessing its same problem. Went to my usual garage to read code and comes up with "fuel trim range exceeded" on both banks so I'm guessing that is O2 sensor-related. The voltages on the pre-cat sensors take time to settle so I think I just need pre-cat sensors. No noticeable air leaks between intake, MAF and engine and the car is at 94k miles so I'm almost 100% sure it's a sensor problem as this is around the time they are due for a change anyway.

Therefore, my question is: Where is the best place for decent sensors at a reasonable price? I went on ECP and they only appear to have bank 2 pre-cat sensor and RealOEM tells me that the pre-cat sensors for banks 1 and 2 are different. Post-cat sensors are same part number. Might give SES a ring, I live in Southampton and there are only round the corner from me - got the others from them, for my E46, and price wasn't too extortionate.

Thanks in advance

 

[Lee]

Do you have a code reader you can use ? I'm asking this because if you can read the live data on fuel trims it will most likely show you theres extra air getting into the system after the maf it should show around 5% long and short trims. Also worth unplugging the maf and seeing if the car runs any better.

I've had these very symptoms recently but I intentionally caused them and these were the codes.

 

[n_mistry]

No code reader I'm afraid, I have been looking to get one (the C110 code reader) but the engine light came up on my golf recently (fixed by replacing sparks and coils) so I thought about trying to get something that works on all cars, like the BlueDriver OBDII guy, but not sure if I can use that in tandem with a round socket adapter?

I'm away this weekend and next but any chance there will be a ZedShed near Southampton open the weekend after (29 feb/1 mar) to pop round and have a chat + meet anyone from the forum?

 

[colb]

Fuel trims high and exceeding range would indicate an air leak somewhere in the intake system or a misreading or duff Maf sensor.
Ideal check for air leaks is a smoke test, successfully found leaks on a 2.2, fixed those on the inlet side only to discover a further leak from a cracked plastic cam cover around No4 plug. Plastic had gone hard and brittle, solved that with a good used cover and new gaskets including the rubber washers under the cover securing bolts. As has been mentioned earlier unplug the electrical connector to the Maf and see if that alters running, it should go to default settings. If running improves then change the Maf, use oem replacement, cheap ones are unreliable.