I still have continued issues with my New Bosch MAF (code P0102) but I spent the last day changing my front O2 sensors.

2x $140 Bosch O2 sensors, bruised and bloodied hands later, my P0154, P0135 and P0155 codes are gone.

Now I have a new friend, P1129, can’t seem to find too much online about this one, lots of posts with confusion about the sensors being on the wrong sides and whatnot. I couldn’t find anything on the sensors to indicate there is a left and a right. And I don’t think I’d have sensors with incorrect polarity out of the box.

One weirdness to report is my scanner reads about 0.350v on Bank 1 Sensor 1, but 0.715 on Bank 2 Sensor 1.
After a few seconds idling I can see it start messing with the short term fuel trim, I start seeing +25% trim on bank 1 and -25% trim on bank 2, then after a little while these go back to 0, the sensors wander further apart again, then the trim comes back to +/-25%

slowly bank 1 works it’s way towards 0 and bank 2 works it’s way up to .900+
so might be wiring issue? Hoping someone has some idea

I may need my adaptions reset by an auto logic or similar. My O2 sensors have been bad for a very long time. And the shot MAF does not help.

im going try warranty the Bosch MAF since it was working perfectly when I first plugged it in. Hopefully a new MAF plus the fixed sensors will result in a better ride, because currently it misses at idle, and bogs down sometimes.

strangely enough, it seems like Bank 1 and 2’s sensor 2 post cat show 1.125 as a voltage permanently on my scanner, I’m not sure I’ve ever seen these any different. Not sure what they should be.

Wouldn’t be sunrised after ages of running rich the cats are stuffed.

 

Testing update.

I was suggested by a friend to swap the bank 1 sensor 1 to bank 2 sensor 1 and vise virsa.

Result. The values have swapped! Bank 1 sees a voltage of about 0.890 and bank 2 sees a voltage of 0.150 or lower.

This would indicate a potentially faulty sensor? I’ve checked the wiring on both New Bosch sensors and they do match in terms of colour. I could swap the grey and black wires round on the faulty sensor to see if this corrects the issue? Keen to hear everyones thoughts on this.

Interestingly after swapping the sensors, I’m seeing activity on the bank 2 sensor 2 now, it dipped down to 1.000v instead of being on 1.125

The STFT goes crazy on first start, but again it’s changed places this time, bank 1 gets -25% and +25% on bank 2, runs awful for a few seconds then the STFT corrects back to zero, I’m guessing this is when the ECU goes back into closed loop and ignores the O2 sensors.

I’ve not had CEL yet at all, and yes I know it works in the test light position.

Im still getting my P0102 and P1129 codes. As well as P0154 which seems to have swapped sides as well as this was P0130 before they swapped sides

keen to hear thoughts

 

Update 3

This morning the car seems to be running better, im guessing my adaptive values cycled over with the 5kms of driving I did yesterday. Running it this morning the values seemed alot more in sync, both around the 0.7-0.8v range while driving, and the STFT was adjusting itself more granularly with values more like -2% to about 9-10% as driving, so it is trying to figure itself out now. P1129 Error went away, so did the P0154, again, weird as I didnt do anything other than swap the sides round on the sensors and leave it for a little while.

I still have P0102 from my bad MAF sensor, unsure if there is any way to revive these sensors. I don't want to be paying another ($750 NZD) by latest quote from my local parts supplier for a MAF that was only 2 months old. Hoping I can get a warranty from BOSCH/Supplier for this part.

I've seen some talk about using VW Golf MAF's on the D2, Im contemplating purchasing one, but about $200 NZD Delivered, so much cheaper, but still quite a risk.

Im just not sure why these MAF's are so prone to killing themselves, I do have a K&N filter and heard some negative things about them, not sure on everyone's thoughts, if I should swap to a standard Paper one instead?

Just wanting to pick some brains and contribute to the form, hoping others with similar issues can learn from my mistakes.

 

I use a K&N filter on my carbureted motorcycle but I personally wouldn’t use one on a fuel injected engine. I know I would for sure over oil it and foul the sensors downstream. I think that even if you’re very careful some oil will go past the K&N.

 

Agree with you there, so much misinformation out there, ive read posts of people saying no never, and read things saying K&N is fine, personally I don't mind having to replace my filter every few years (or whatever the service life is) they often aren't that expensive.

 

I haven't heard back from my local parts supplier about a replacement MAF, so still waiting on them and the distributor to arrange this, in the meantime, I have purchased a "PIERBURG 7.22684.10.0." from Trodo.com and a Generic "OEM Discovery 2 V8" Maf from Aliexpress that uses the same part number as the Bosch part, I have done this as a temporary measure to compare the Aliexpress Maf to Factory BOSCH and to compare the PIERBURG replacement (from VW/Merc) to the BOSCH Maf.

I found the Pierburg MAF suggestion from another Forum here so willing to test and see if this can be a recommended replacement for the expensive BOSCH Maf's