2004 xc90 - Red Warning light when starting engine, turns off after 1-3 minutes of idling

[iamshmo]

Hello all -

I am looking for some support with my 2004 xc90. Within the last week, the warning symbol has been turning on when I first start my car. It will remain on for about a minute to a few minutes while the engine is idling/warming up, and then it will turn off. I drove it once after this and it ran fine (normal vitals, normal engine temp, normal RPMs), but I have decided to not push it until I get to a shop (later this week). The DIM/Instrument panel has some quirks and I am unable to read the info panel anymore.

Backstory:
This care has been in the family for about 15 years. It has been well maintained, a new engine was installed in approximately 2010. There are currently 240894 miles on it. It has been a local commuter for the past 5 years, but I recently drove a long distance with it (610 miles) because we moved. I got an oil change, tires/brakes checked, and a new Alternator and timing belt installed before the trip. The car drove just fine the whole way.

I will now be working with a new mechanic in a small town, and I hope to get some advice about possible diagnostics before going in. Any ideas/advice will be appreciated!

[ggleavitt]

Instrument panel (DIM) might be a cold solder joint on one of the chips, some areas go wonky (clock as another example) and the issue progressively gets worse until the entire DIM goes blank (experienced this on a '03 S80). That your information windows is not working may be a symptom of a pending failure. The DIM can be repaired by Xemodex if it's warranted- https://xemodex.com/us/products-for-volvo/ , issue is not uncommon.

Warning symbol means a problem which should normally equate to an error code. When you get to the mechanic, they should be able to see what's being reported. Volvo likes to use their own proprietary codes (module centric, ECM-xxxx as one example) for errors, you'll get a standard P-xxxx OBD output if you put a generic reader on the port. Go here- https://www.matthewsvolvosite.com/volvo ... wer-codes/ for a decoder ring of sorts.

Good luck with your resolution and feel free to post the codes once you pull them.

[iamshmo]

codes received from the mechanic:

CEM 8F52/ RELAY, HEADLAMP CLEANING; SIGNAL TO LOW OR MISSING

ECM-5000 PRESSURE SENSOR
ECM-2AIA REAR OXYGEN SENSOR\

BCM-0080 LATERAL ACCELEROMETER SENSOR; OFFSET
BCM-0114 COMMUNICATION W/AYC-SENSOR; SIGNAL MISSING

UEM-0004 SIREN
UEM-0005 SUNROOF

ICM-DC02/ CONTROL MODULE COMMUNICATION; MISSING
ICM-DC01/ CONTROL MODULE COMMUNICATION; FAULTY SIGNAL

[ggleavitt]

My guesses, based on what you reported:

CEM 8F52/ RELAY, HEADLAMP CLEANING; SIGNAL TO LOW OR MISSING
Headlight washer coil open or washer connector to CEM open or a bad relay FST2 (unlikely).

ECM-5000 PRESSURE SENSOR
This is the A/C pressure sensor, located on the top of the drier assembly adjacent to the radiator. Might be cable disconnected or sensor failure, suggested as signal fault.

ECM-2AIA REAR OXYGEN SENSOR
Per VIDA-The control module checks the rear heated oxygen sensor (HO2S) dynamics. The control module checks that the probe has registered both lean and rich fuel mixtures. If this is not the case, the control module alters the fuel mixture. Diagnostic trouble code (DTC) ECM-2A1A (bank 1) is stored if the rear probe is still not registering lean (signal too low) or rich (signal too high) fuel mixture. At fuel shut-off, the probe must show lean fuel mixture. Diagnostic trouble code (DTC) ECM-2A1A (bank 1), signal missing, is stored if the switch over time from lean to rich fuel mixture is too long.
This might be your red light that goes away.

BCM-0080 LATERAL ACCELEROMETER SENSOR; OFFSET
I think this error is coming from the next error.
BCM-0114 COMMUNICATION W/AYC-SENSOR; SIGNAL MISSING
I think the active yaw sensor under the floor has either failed or the connectivity to the BCM is missing.
If your message center window was working, you would see a literal message about traction control being disabled.

UEM-0004 SIREN, UEM-0005 SUNROOF
I’ll guess that your siren catastrophically failed at some point (internal battery leaks and corrodes the PCB) and has corrupted the LIN bus to the UEM or a fuse has been disconnected. Sunroof work or does not work?

ICM-DC02/ CONTROL MODULE COMMUNICATION; MISSING
ICM-DC01/ CONTROL MODULE COMMUNICATION; FAULTY SIGNAL
This is your infotainment module (radio face, CD player) reporting a break in the MOST fiber network (cable, power, module failure). If your mechanic has a VIDA/DICE unit, they can run a diagnostic and tell you which module is causing the fuss.

That’s what I see. Motor a 5 cylinder or a 6 and has this vehicle experienced flooding or a sunroof leak in its recent life?

[iamshmo]

Thank you so much for all of this info.

Is there a way that I can test/check the lean/rich fuel mixtures? This is a part of the emissions system, right? I had a battle with the EVAP system that I finally got under control last year. (new hose, valve, and two fuel caps).

The sunroof has not worked for years, It used to experience leakage that resulted in a pooling of water in the passenger footwell (2017-2018) but I resolved that by just duct-taping the gap around the sunroof and regularly clearing debris in/near the vents. I have not had a leak in the last 5 years.

[ggleavitt]

For testing fuel/air ratios, it's easy enough to see the performance in VIDA (software that interfaces with the vehicle via a DICE unit) if you have access. Might be some other readers that can pull metrics as well, VIDA is all I know.

If I were to "guess" at the rear O2 sensor problem, I might suggest sensor degradation given the age of the vehicle. Not sure what motor but if you replace the sensor, use a Bosch part, it's original equipment and a little cheaper than Volvo blue box. Might be PN 8677894 but you'll want to validate for yourself. Example here- https://www.ipdusa.com/products/8405/Re ... 894-112275