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gschotland

Did I kill my oxygen sensors?

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Last year I replaced all four 02 sensors (w/ OEM connectors) on my '02 S at 70k mi due to a CEL. Recently at 79k I got CEL codes P0154, P1118 and P1119, all Bank 2 sensor faults. I read that these may be caused by a failed or failing AOS. Sure enough, there was a strong vacuum when I removed the oil filler cap, but none of the telltale mushroom clouds from a totally failed AOS. The car's been running great and gas mileage has been fine (low 20s), so I thought I had a little time. Using the Durametic I reset the codes but they came back immediately.

After 800 miles I finally found the time to replace the AOS. Once again I reset the fault codes a few times, but they came right back. The car hasn't been driven since the AOS was replaced, but it was started and run for 10 minutes to get it up to temperature before the codes were cleared; this made no difference.

Did my failing AOS cause permanent damage to the Bank 2 sensors, necessitating replacement? I'm not looking forward to shelling out another $300 for two new ones after only 10k miles.

I was thinking it would make sense to swap the Bank 1 & 2 sensors to see if the faults move to Bank 1. Before going through all that, is there a possibility the codes could go away by themselves with a couple of "drive cycles"? If so, how long should those cycles be?

Thanks!

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I think that is a good idea to change O2 sensors, reset the the codes and see if they appear on the other bank. You may also have a vacuum leak, a faulty gas cap or leaking oil filler tubes. A bad AOScan reign havoc on oil filler tubes. Let us know what you find out.

Edited by kbrandsma

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I seriously doubt that replacing the O2 sensors will fix this; two of the codes (0154 and 1119) are telling you that there may be a wiring or connector issue in the O2 circuits:

P0154 is the code for the interruption of the signal from the senor ahead of the 3 way cat on bank 4-6.

P1119 is the code for a non functioning sensor heater.

Edited by JFP in PA

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I'm going to try swapping left and right first and see what happens.

Is it advisable to try and clean the sensors or let any residue burn off the natural way?

JFP, I've seen a number of posts regarding these and related codes in which the end result almost always seems to be replacement of the sensors due to issues with their connectors (not that I'm looking for a reason to replace them). It's just a little more than odd that both Bank 2 sensors developed issues at precisely the same time and two of those issues are the same (P1118 & P1119). Do wires to these two sensors alone meet at one point elsewhere in the circuit? While changing the AOS I saw the connector which runs to the O2 sensors (I think), but I'm assuming it goes to all four.

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I'm not sure about there being a common junction for the wiring, as the signal and heater wiring serve different purposes I would expect not; but there are diagnostics to check for the sensor signal and heater voltage using a multimeter. I'd be running them before spending more money on sensors....

Edited by JFP in PA

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This evening I swapped the Bank 1 & 2 sensors. While doing this I inspected each sensor and saw no oily residue or any differences in their appearance. The car fired up fine, I cleared the codes, let her come up to temp and then checked the codes again. This time they were P1115, P1117 (both Bank 1) essentially the same codes I had prior to the swap on Bank 2. There was no CEL.

I reset the codes again, took the car out for a 20 min drive and re-read the codes. Same P1115 and P1117 but now P0134 as well, which appears to be the Bank 1 version of P0154. I let the car rest for an hour, reset the codes again and then took another 20 minute drive. This time I got P1115, P1117, P0134, and then P0140, which is a Bank 2 O2 sensor code. Thankfully no CEL so far. Things are looking up!

Is it safe to assume that the two sensors now on Bank 1 are toast?

Any suggestions on the cause of P0140?

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P0140 says correct P1117 and see if the problem persists.

Something chew on wiring? These were OEM Bosch with pigtails...not some off brand right? No homebrew connections? Correct part numbers?

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P0140 says correct P1117 and see if the problem persists.

Something chew on wiring? These were OEM Bosch with pigtails...not some off brand right? No homebrew connections? Correct part numbers?

They are non-Bosch with the correct OEM type connectors (no homebrew connections). I'll be replacing them with Bosch with OEM connectors. I couldn't see any issues with any of the wiring.

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P0140 says correct P1117 and see if the problem persists.

Something chew on wiring? These were OEM Bosch with pigtails...not some off brand right? No homebrew connections? Correct part numbers?

They are non-Bosch with the correct OEM type connectors (no homebrew connections). I'll be replacing them with Bosch with OEM connectors. I couldn't see any issues with any of the wiring.

Mike is right. There is always problems with any non- OEM O2 sensors. It is better to re-install with orginal parts. Also don't spray any electrical cleaner on connectors but, rather connect and reconnect a few times to ensure a good connection.

Edited by kbrandsma

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Ordered two new Bosch sensors today and will report back after I get them installed.

kbrandsma says no connector cleaner. I think I'll try his suggested contact enhancement method before Stabilant 22, which I'd never heard of but looked up; I'm skeptical of magic potions. :eek:

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