O2 sensor/CEL 1-2-2-1 code -- fix ...

[gale]

My wife bought an e36 325ic (m50) from a local club member & the car had been sitting for many months & threw the O2 sensor fault code & failed the HC emissions test the 1st time. The shop said O2 sensors rarely go bad (I did not know that) & to simply unplug & re-seat the sensor connector & the fault usually goes away. I did that & reset the code memory & sure enough, it worked! I had her take it out & "drive it like you stole it" & sure enough it passed with all numbers down in the low zero's.

Guess sometimes the connectors can get corroded from spray-washing the engine. Yet another place to use Stabilant 22 -- or maybe it just needed to have a fresh tank of gas & driven hard (& not put away wet) ;)

[Bill R.]

o2 sensor connector. everywhere else is fine.




My wife bought an e36 325ic (m50) from a local club member & the car had been sitting for many months & threw the O2 sensor fault code & failed the HC emissions test the 1st time. The shop said O2 sensors rarely go bad (I did not know that) & to simply unplug & re-seat the sensor connector & the fault usually goes away. I did that & reset the code memory & sure enough, it worked! I had her take it out & "drive it like you stole it" & sure enough it passed with all numbers down in the low zero's.

Guess sometimes the connectors can get corroded from spray-washing the engine. Yet another place to use Stabilant 22 -- or maybe it just needed to have a fresh tank of gas & driven hard (& not put away wet) ;)

[gale]

Thanks Bill, good to know. I never would have suspected they'd route air intake to the O2 sensor thru the connector/wires -- guess it makes sense somehow.

BTW, would you have a source for a comprehensive repair/instruction/troubleshooting for the e36 convertible top mechanism. I gather they're rather problematic & most people end up putting them up & down manually. Bentley's is lacking, as usual.

Cheers!

Don

[Bill R.]

e36 top file.






Thanks Bill, good to know. I never would have suspected they'd route air intake to the O2 sensor thru the connector/wires -- guess it makes sense somehow.

BTW, would you have a source for a comprehensive repair/instruction/troubleshooting for the e36 convertible top mechanism. I gather they're rather problematic & most people end up putting them up & down manually. Bentley's is lacking, as usual.

Cheers!

Don

[fujioko]

From what I read it sounds like the O2 sensor is getting its reference oxygen supply via the harness. Hmmm…. I would imagine that zip-ties on the harness would impede the flow as well?

[BillionPa]

that is what it sounds like, but my new O2 sensors came with zip ties in the package! (Bosch)

[gale]

e36 top file.

Thanks Bill!

[Bill R.]

.
Thanks Bill!

[ryan roopnarine]

bill might have something to say about this, gale, but i've used this on a couple of dying oxygen sensors now, and its brought them back to functional life (along with a couple of MPG). this is completely winfred's procedure, he mentioned it on this board, but i can't find the specific post to cite. he says to use a wire brush to clean the body up (i do it to a shine) along with a pick to clean the slots/holes. he then uses a torch to blow heat it up well, then blow it out with compressed air. i don't have shop gasses, so i use propane and heat the sensor until "sparks" stop burning off (if you remember from college chem I, they probably had you (everybody) heat up sticks soaked in ions until ion characteristic "sparks" come off of them. i just heated the sensor up until it stopped throwing off these "sparks". then hit it with the compressed air.

then again, this was done on cars that had nice, un-rusted oxygen sensors that came off in 1-2 minutes without lubricants. might not be worth it if the sensor is stuck.

[gale]

If you use a wire brush, be sure to use a soft brass-bristle brush. A steel brush could go right thru the platimum plating. Also, I think there must be more than 1 style of O2 sensor leads. My old factory one from the e32 has about 4 feet of cable which are nothing more than 4 separate teflon insulated wires, covered with an outer black PVC shrink tube, which lacks about 1/2" from each end. The connector to the engine/chassis wire harness is nothing more than a plastic "Cannon" connector of sorts, with the pins simply crimped onto the ends of the wires.

The new e36 sensor has a short 12" cable which has a white teflon outer jacket sealed at each end of the O2 sensor and the connector. I guess that must be the type that the TIS cautions against using Stablilant 22a. There's no way my older e32 4-footer is a leak path that could clog a reference bleed.

[Bill R.]

other cars too. They all caution against using any conductive grease on o2 connectors for this reason. The oxygen path is through the individual braided wires inside each wires insulation not through the jacket covering the whole thing, They don't need much o2, its only for a comparative reference.



If you use a wire brush, be sure to use a soft brass-bristle brush. A steel brush could go right thru the platimum plating. Also, I think there must be more than 1 style of O2 sensor leads. My old factory one from the e32 has about 4 feet of cable which are nothing more than 4 separate teflon insulated wires, covered with an outer black PVC shrink tube, which lacks about 1/2" from each end. The connector to the engine/chassis wire harness is nothing more than a plastic "Cannon" connector of sorts, with the pins simply crimped onto the ends of the wires.

The new e36 sensor has a short 12" cable which has a white teflon outer jacket sealed at each end of the O2 sensor and the connector. I guess that must be the type that the TIS cautions against using Stablilant 22a. There's no way my older e32 4-footer is a leak path that could clog a reference bleed.

[ryan roopnarine]

If you use a wire brush, be sure to use a soft brass-bristle brush. A steel brush could go right thru the platimum plating. Also, I think there must be more than 1 style of O2 sensor leads.

i don't own a steel wire brush, so i don't think i'll have a problem. just so everyone understands me, i wasn't suggesting that anyone do that to an oxygen sensor that they cared about. my mentioning that it worked on several cars was just me ensuring that replacing an oxygen sensor (on a particular car) would end an oxygen sensor code. m50 throws off the oxygen sensor code for any widdle air leak. my comment about the mpg gain was to reinforce this, as that usually seems to be the telltale that an o2 sensor needed replacing (in addition to the code, of course). not anything i've ever had to do to the e34.