2007 S40 - "The Ratmobile"

[BG123]

First time posting here but long time follower, reading other people’s issues has helped me immensely. Hoping the group can provide some insight on my own set of bizarre issues this time. Here’s the full rundown:

2007 Volvo S40 2.4i automatic with 103,000 miles. Haven’t had any major issues aside from the dreaded sunroof leak (which forum help and $2 of tubing saved me from a $500 dealer bill) and a couple of sway bar replacements.

Initially started when I noticed a couple of thumps shortly pulling away from my street parking spot. The car drove normally after that on a short trip to pick up dinner. Early the next morning the car started normally again then right once I drove away the engine cut out and I was unable to restart the car. The engine would only sputter and was unable to fire. I was forced to have the car towed to my local mechanic.

The shop spent 2 hours trying to diagnose the issue - ultimately they discovered that the sound I heard was a rat that had been hiding out under my hood. The mechanic showed me a picture of the dead rat in the engine compartment - and a few bits and pieces on some of the components. They deduced that somehow the rat had gotten itself into a spot where it caused the timing belt to jump - they said it was off 6 teeth. They said they inspected the surrounding hoses and wires and did not notice any other damage, nor any valve damage caused by the jumped timing. I gave them the go-ahead to do the full timing belt replacement (including water pump) at a hefty price tag, figuring that it should be done around this time anyway.

Well, I picked up the car last week and drove it home about a mile and it seemed fine. On the weekend I drove it further to get an emissions test - about 3 miles in I was forced to stop quickly at a red light and the engine cut out. I was able to turn the car off and get it restarted, the “reduced engine performance” and “engine service required” notifications popped up and it went into limp mode. A few miles further, the engine started jerking and sputtering and wouldn’t go over 15mph; I was forced to pull into a parking lot and call for a tow.

I brought it back to the shop that replaced the timing belt - they drove it twice for about 20 minutes but were unable to recreate the issue. They pulled a p0121 code and Volvo codes 914c (Electronic Throttle Module), 9918 (Throttle Unit), and 950c (Accelerator Pedal Pos Sensor). They suggested I replace the ETM and quoted $600 for the part. I’ve been reading up on the wealth of ETM and MAF knowledge here, but I’m skeptical that this is the issue (or the only issue). Seems like quite a coincidence that the part would fail at the same time that a rat was found under the hood. I’m worried that there could be some wiring or hoses that my rodent friend started gnawing on before he expired that could be causing some issues.

I’m considering taking it into a Volvo dealer for an ETM sweep to try to determine if that’s ultimately the issue. Does anyone have any other suggestions for trying to isolate the problem or directions to point the dealer in when asking them to run some diagnostics?

Thanks,
Brian

[RickHaleParker]

Your code format is butchered. Volvo DTCs have the format XXX-YYYY as in ECM-914C. Get the unbutchered codes.
XXX = The control module. YYYY = the trouble code for XXX.

[BG123]

ECM-914C, ECM-9918, ECM-950C.

[RickHaleParker]

P0121 = ECM-9210

ECM-9210 , ECM-914C, ECM-9918 & ECM-950C.

---------------------------------------------------------------------

ECM-9918 Throttle unit. Faulty signal

Possible source
Other diagnostic trouble codes (DTCs) are stored, caused by the throttle unit being deactivated.

---------------------------------------------------------------------

ECM-9210 Electronic throttle unit, potentiometer 1. Faulty signal
Possible source

• Contact resistance or oxidation in the terminals between the engine control module (ECM) and the electronic throttle unit
  The signal cables are short-circuited to each other
  Damaged throttle unit.

----------------------------------------------------------------------------
ECM-914C Throttle unit. Signal too high
Possible source
Signal too high

• Contact resistance or oxidation in the terminals
  Short-circuit to voltage in the signal cables
  Short-circuit to battery voltage in the power supply
  Open-circuit in the ground lead
  Short-circuit to supply voltage in the ground lead
  Damaged throttle unit.

Signal too low

• Contact resistance or oxidation in the terminals
  Short-circuit to ground in the signal cables
  Open-circuit in the signal cables
  Short-circuit to ground in the power supply
  Open-circuit in the power supply
  Damaged throttle unit.

Faulty signal

• Contact resistance or oxidation in the terminals
  Damaged throttle unit.

--------------------------------------------------------------------



ECM-950C Accelerator pedal (AP) position sensor. Analog signal

Possible source

• Analogue signal too high
  Troubleshoot the central electronic module (CEM).

Analogue signal too low

• Troubleshoot the central electronic module (CEM).

Pulse width modulation (PWM) signal too high

• Short-circuit to ground in the signal cable.
  Open-circuit in the signal cable.

Pulse width modulation (PWM) signal too low

• Short-circuit to ground in the signal cable.
  Short-circuit to voltage in the signal cable
  Open circuit in the signal cable
  Open circuit in the voltage feed.
  Open circuit in the ground cable.
  Damaged accelerator pedal (AP) position sensor.

Incorrect pulse width modulation (PWM) signal

• Loose connections or contact resistance in the terminals on the pulse width modulation (PWM) signal cable
  Interference on the pulse width modulation (PWM) signal cable
  Damaged accelerator pedal (AP) position sensor.

Comparison error

• Loose connections or contact resistance in the terminals on the analog signal cable
  Malfunction of voltage feed to the analog signal.
  Malfunction in the analog signal's ground
  Malfunction in the pulse width modulated signal cable between the engine control module (ECM) and the accelerator pedal (AP) position sensor
  Damaged accelerator pedal (AP) position sensor.

Incorrect signal

• Malfunction in the control area network (CAN) communication between the engine control module (ECM) and the central electrical module (CEM)
  Troubleshoot the central electronic module (CEM).

[BG123]

Thanks for posting, this is helpful. Seems to confirm my suspicion, at least I'll have a starting point for the technicians to examine the wiring.