07 GL450 very odd behavior - could be PCM? or?
Thread Starter
Member
Joined: Aug 2018
Posts: 90
Likes: 7
From: Arizona
2007 GL 450 (former) and 2012 E550 Coupe
07 GL450 very odd behavior - could be PCM? or?
I've got an 07 GL450 with 215K miles. It has had been a solid car with really no problems or issues since I've owned it (bought it at 180K miles) other than me replacing the front airbags with Arnott's. The previous owner took really good care of it. Has zero leaks.
However, last week it started doing something odd. When driving at about 45 MPH, ALL the dash lights flashed (and I do mean ALL - seatbelt light, etc - all of them), the car beeped and it auto-applied the brakes for a second. Within 2 seconds, all the dash lights cleared and it drove fine for the remainder of the 10 minute trip. When I got home, I looked it up and saw many posts saying that was the pre-collision assist and that it would happen on occasion and not to worry about it, so I disregarded it. This week, it started doing that again, but more often. It now happens about 75% of the time I drive it and along with it, the CEL popped on and the car started running very rough - felt like a misfire. I plugged in my OBDII and pulled the codes:
Great. I got home, turned it off and the next morning, started it up, but the CEL was gone and it was running just fine - wasn't running rough, no issues. It drove fine that whole day.
The following day, the same thing happened with the pre-collision thing, the dash lights and the beep, then the CEL and engine running rough. When I got home, I pulled the codes again, but this time they were different:
Completely different - even a different cylinder on the misfire.
Is my PCM going bad? Something else? Admittedly, I did bypass an O2 sensor about a year ago because the cats are pretty much dead due to mileage, but haven't had an issue with that.
Thoughts on what this might be?
However, last week it started doing something odd. When driving at about 45 MPH, ALL the dash lights flashed (and I do mean ALL - seatbelt light, etc - all of them), the car beeped and it auto-applied the brakes for a second. Within 2 seconds, all the dash lights cleared and it drove fine for the remainder of the 10 minute trip. When I got home, I looked it up and saw many posts saying that was the pre-collision assist and that it would happen on occasion and not to worry about it, so I disregarded it. This week, it started doing that again, but more often. It now happens about 75% of the time I drive it and along with it, the CEL popped on and the car started running very rough - felt like a misfire. I plugged in my OBDII and pulled the codes:
Current Fault Log
------------------
P0432: Main Catalyst Efficiency Below Threshold (Bank 2)
Pending Fault Log
------------------
P0302: Cylinder 2 Misfire Detected
Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
P0629: Unknown code - More information may be available on the web
P0645: A/C Clutch Relay Control Circuit
P0942: Unknown code - More information may be available on the web
P0946: Unknown code - More information may be available on the web
P1596: Unknown code - More information may be available on the web
------------------
P0432: Main Catalyst Efficiency Below Threshold (Bank 2)
Pending Fault Log
------------------
P0302: Cylinder 2 Misfire Detected
Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
P0629: Unknown code - More information may be available on the web
P0645: A/C Clutch Relay Control Circuit
P0942: Unknown code - More information may be available on the web
P0946: Unknown code - More information may be available on the web
P1596: Unknown code - More information may be available on the web
The following day, the same thing happened with the pre-collision thing, the dash lights and the beep, then the CEL and engine running rough. When I got home, I pulled the codes again, but this time they were different:
Current Fault Log
------------------
ECU reports no current faults
Pending Fault Log
------------------
P0308: Cylinder 8 Misfire Detected
P2610: M/PCM Internal Engine Off Timer Performance
Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
P0629: Unknown code - More information may be available on the web
P0645: A/C Clutch Relay Control Circuit
P0661: Intake Manifold Tuning Valve Control Circuit Low (Bank 1)
P1594: [BMW] B Camshaft Position Actuator Control Open Circuit Bank 2
------------------
ECU reports no current faults
Pending Fault Log
------------------
P0308: Cylinder 8 Misfire Detected
P2610: M/PCM Internal Engine Off Timer Performance
Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
P0629: Unknown code - More information may be available on the web
P0645: A/C Clutch Relay Control Circuit
P0661: Intake Manifold Tuning Valve Control Circuit Low (Bank 1)
P1594: [BMW] B Camshaft Position Actuator Control Open Circuit Bank 2
Is my PCM going bad? Something else? Admittedly, I did bypass an O2 sensor about a year ago because the cats are pretty much dead due to mileage, but haven't had an issue with that.
Thoughts on what this might be?
Thread Starter
Member
Joined: Aug 2018
Posts: 90
Likes: 7
From: Arizona
2007 GL 450 (former) and 2012 E550 Coupe
