O2 sensor and turbo control code

Post by **donc** » 11 Feb 2021, 11:48

The symptoms began with a check engine light showing large evap leak. I put off the repair because I read that the evap canister is in the most inconvenient place on the car, right by the fuel tank above the rear axle.

After a long trip recently, the rear hatch handle that signals the hatch light to come on failed, leaving the light on and running the battery to nothing. After the trip, I disconnected the hatch lamp and trickle charged the battery for the weekend. Now I no longer have the evap code, but I now have the following codes:

ECM-221B Rear O2 sensor aging, bank 1 – signal missing
ECM-222B Rear heated O2 sensor (ho2s), bank 1 – signal missing
ECM-600B Turbocharger (TC) control valve – signal missing

I’m guessing that these codes may be totally unrelated to the previous issue(s). I disconnected that battery for 10 minutes with the positive and negative cables zip tied together and hooked back up with the key in position 2 and the doors shut. The codes remain.

I am ordering an ECM removal tool to remove, inspect, clean contacts. I guess I could replace the original O2 sensor and turbo control valve, but could these codes be the result of the original evap code or even some other issue? Any advice would be appreciated.

Post by **firstv70volvo** » 11 Feb 2021, 15:18

donc wrote: ↑11 Feb 2021, 11:48 The symptoms began with a check engine light showing large evap leak. I put off the repair because I read that the evap canister is in the most inconvenient place on the car, right by the fuel tank above the rear axle.

After a long trip recently, the rear hatch handle that signals the hatch light to come on failed, leaving the light on and running the battery to nothing. After the trip, I disconnected the hatch lamp and trickle charged the battery for the weekend. Now I no longer have the evap code, but I now have the following codes:

ECM-221B Rear O2 sensor aging, bank 1 – signal missing
ECM-222B Rear heated O2 sensor (ho2s), bank 1 – signal missing
ECM-600B Turbocharger (TC) control valve – signal missing

I’m guessing that these codes may be totally unrelated to the previous issue(s). I disconnected that battery for 10 minutes with the positive and negative cables zip tied together and hooked back up with the key in position 2 and the doors shut. The codes remain.

I am ordering an ECM removal tool to remove, inspect, clean contacts. I guess I could replace the original O2 sensor and turbo control valve, but could these codes be the result of the original evap code or even some other issue? Any advice would be appreciated.

Have you checked the O2 sensors fuse in the engine compartment?

Post by **donc** » 11 Feb 2021, 16:13

Thanks for the suggestion. I just checked all of the fuses under the hood and all of the fuses at the left of the dash inside the cabin. All good. Also, today I pulled the ECM and all of the connections looked good/uncorroded. I sprayed contact cleaner on the receptacles and moved the ECM in and out several times. I'll hook up the battery in a bit and rescan for the codes.

Post by **donc** » 11 Feb 2021, 17:03

I have also read that having a crack in the tube between the air filter box and turbo can produce erratic symptoms in the turbo. I just hope its not a short in the wires somewhere. I just hate running down electrical shorts!

Post by **SuperHerman** » 12 Feb 2021, 00:18

Do you have a scanner? Your codes, specifically "signal missing", points to a hard fail on the parts. It could be wiring or a fuse, but the first impulse is a faulty part. But, due to the failed battery issue, I would clear the codes and see if they come back.

You can test the O2 sensor and the wiring to see if you are getting the correct signals.

For the TC valve you can do the same - you can also pull it and apply power to it.

Post by **donc** » 13 Feb 2021, 08:10

Update: i installed a new TCV and hooked up the battery. I ran the scan again. Oddly enough one of the O2 sensor codes disappeared:

Disappeared: ECM-221B Rear O2 sensor aging, bank 1 – signal missing
Present: ECM-222B Rear heated O2 sensor (ho2s), bank 1 – signal missing
Present: ECM-600B Turbocharger (TC) control valve – signal missing

I'm at a loss. Unless all of these sensor wires run along the same path and were somehow compromised?

Post by **SuperHerman** » 13 Feb 2021, 12:07

You are going to have to go old school and VOM your wiring and suspect parts. There are write ups on the forum on where to check and what readings you should be getting.

It looks like you have a wiring harness issue. Checking for damage, shorts, corrosion and proper signal voltage is the next step.

Post by **donc** » 21 Mar 2021, 09:34

Resolution! Thanks firstv70volvo and SuperHerman for your suggestions and help. All issues are resolved.

The ECM-600B Turbocharger (TC) control valve – signal missing was the result of one of the harness wires at the plug for the TCV valve was disintegrated and the other wire had multiple breaks in the insulation at the plug. I can't believe I missed that on inspection!

The ECM-222B Rear heated O2 sensor (ho2s), bank 1 – signal missing was resolved by disassembling the O2 connector plug and spraying with brake cleaner and then DeOxit contact cleaner. Evidently it was fouled with oil from the formerly leaking rear main seal.

The old rear main seal was flopping around the rear shaft and I believe that its probable that air was entering (and oil exiting!) causing a leaking vacuum EVAP code. That code has disappeared.

All in all, this is a driver's car. I love it when its on its game. I hate it when there is a problem and it is oh now what. Then again, the car is 15 years old and will have issues. I am bound and determined to add another 100,000 miles to it and enter the 300k arena. Let's hope for the best! Thanks again!