Hi guys,

Would appreciate your help with next diagnosis steps for my 2003 Saturn Vue 2.2L. It's running super rough below 2000rpm and especially at idle, although it seems to be okay when the engine is cold for the first few minutes of driving strangely enough. It feels very similar to the symptoms from a couple of years ago when I had the ignition pack replaced. However, I was reading these things should last longer than a few years so I'm thinking it must be something else now.

I pulled the codes and got:
P0378
C3F00
P0300
P0420

I see the first one is "Timing Reference High Resolution Signal "B" Intermittent/Erratic" which doesn't seem to relate specifically to coil packs. I've also seen online that replacing the ICM can solve the issue.

Has anyone had this problem and could suggest next steps? If I just need to start replacing parts, where should I start? the ICM?

Any help appreciated, thanks

 

That code (P0378) refers to the crankshaft position sensor sending an unreliable signal to the ECM. It could be the sensor itself, or bad connection to the wiring, or the wiring going from the sensor to the ECM. The sensor is located on the front of the engine below the intake manifold, toward the transmission. It's hard to see and work on, but you should check that the connector is firmly attached and that the wiring looks intact. If this looks good, pull the sensor (held in place by one bolt) and check the portion that is inserted into the engine for damage or debris.

 

Just to update everyone on the end result, it was actually just the ignition coil pack. Replaced that and everything was fine.

 

Thank you for the closure.

 

That's the second time for the coil pack to be replaced? Where in the world are you getting them?