P2111 After O2 Sensor Replacement

ChrisRicc · Post by **ChrisRicc** » 30 Mar 2019, 15:06

I'm new to the site. I appreciate your time and help.

Replaced both O2 sensors on my 04 V70R. It was a blast getting to the connectors. Now the car is throwing a P2111 TAC System Stuck Open code while running rough and seemingly in limp home mode.

Any ideas as to why the replacements led to the new code? Never had a problem to date with the throttle body or TPS.

Thanks much.

Post by **RickHaleParker** » 30 Mar 2019, 16:55

1. Clean the electrical connector to the Throttle unit.
2. Check the wiring to the Throttle unit.
3. Clean out the Throttle unit

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P2111 = ECM-91B7 Throttle unit. Faulty signal

Diagnostic trouble code (DTC) information

Condition
Diagnostic trouble code (DTC) ECM-91B7 is stored if the engine control module (ECM), when attempting to adapt the throttle unit, registers that the movements of the throttle is impeded or that the return spring in the throttle unit is not functioning correctly.

Substitute value
Depending on the fault, the engine control module (ECM) can cut off the supply to the damper motor in the throttle unit. The throttle will then attempt to set itself to the return position.

PPossible source

1. The throttle is sticking or is blocked (oil film, dust etc.)
2. Contact resistance or oxidation in the terminals between the engine control module (ECM) and the throttle unit
3. Open-circuit, short-circuit to ground or short-circuit to supply voltage in the wiring for the damper motor in the throttle unit
4. Short-circuit to each other in the wiring for the damper motor in the throttle unit
5. Defective throttle unit

Fault symptoms

Driving/Hesitates/surges/Unsure when/at all times
Driving/Engine stalls/During acceleration
Starting/Engine does not start/Unsure when/at all times
Driving/Engine stalls/At steady speed
Warning lights and chimes/Malfunction Indicator Light ("Check engine" light) indication/no indication

tardcart · Post by **tardcart** » 30 Mar 2019, 18:39

there is such thing as coincidence, however the best place to start with what you last did. 90% of the time its that or something you did while doing that. You need to give more info. Bosch/volvo ox sensor? why did you replace them(and not just one if getting that code)?
what did you move while getting to the connectors?

ChrisRicc · Post by **ChrisRicc** » 30 Mar 2019, 21:17

Hi. Thanks for the responses. Sorry about the limited info.

Prior condition = had check engine light on and thrown emissions code. Knee jerk, replaced both O2 sensors with Bosch units to affect passing of required emissions test here in CO. Both were extremely corroded. Removed airbox and MAF to gain access. MAF snapped its retaining clip in the process. CO is hard on old plastics in addition to my less than adept skills as a mechanic.

I agree the coincidence thing is less likely. If the throttle unit coincidentally had a problem exactly when I replaced the O2 sensors, that would surprise me. Stranger things have happened, though. I think I hit something or broke something with my too left hands. I've disassembled the airbox and am heading back through the replacement process from earlier to see what might have happened.

No known interaction between O2 sensors and throttle unit that you all know of?

DrDan · Post by **DrDan** » 31 Mar 2019, 04:34

Just a thought, but the faulty signal at throttle might be spurious. I have it sometimes and it does not seem to cause trouble.

Did you disconnect the battery to trigger new adaptation of A/F mixture? Because, after replacing a faulty sensor with a good one the learned adaptation could be way off, leading to rough running.

I suggest resetting ECU and see if things clear up.

Post by **abscate** » 31 Mar 2019, 04:39

Definitely clear codes and see if they come back

No connection between OXS and throttle body, correct.

ChrisRicc · Post by **ChrisRicc** » 31 Mar 2019, 11:18

Great idea. I'll give it a go today.

ChrisRicc · Post by **ChrisRicc** » 01 Apr 2019, 19:50

Well, I reset the ECU and cleared the codes. The car started right up and revved like it normally would. I ran it for 10 minutes and it still revved with no codes registered. Before letting any irrational happiness set in, I shut it down and tried it again. It started fine and then after a couple clicks or blips from the engine, it then went back into no-rev mode and then threatened to stall. It wouldn't rev over 2000 RPM. Again, it's reading P2111.

Perhaps it is the unlikely coincidence of throttle unit needing a good cleaning?

I neglected to mention anywhere, the car has 190k on the odometer.

Post by **abscate** » 02 Apr 2019, 03:45

Definite throttle body cleaning needed

ChrisRicc · Post by **ChrisRicc** » 07 Apr 2019, 16:05

As a follow-up to my recent posts above, I pulled the TB in hopes being able to clean, restore, and all codes vanish. What I found is shown in the attached picture. I don't think it's ever been cleaned. My question to you fine folks is this... Is this unit beyond help and in need of replacement, or can it be salvaged with the proper cleaner?