Been struggling with this issue for the past several winters and have spent a ton of time trying to figure it out. This ONLY ever happens in cold weather (below approx. 10C / 50F). The colder it is, the worse it gets. Here are the details.
1 - Cold weather ONLY (below 10 deg. C) - no code
2 - Try to start the car. Struggles and won’t idle. It’ll “catch” briefly but won’t run. Keep trying and trying…
3 - Eventually, the CEL comes on and the engine starts right up and will idle.
4 - CODE : P0340 - Camshaft Position Sensor Circuit A.
5 - At this point, if I clear the engine code it will immediately sputter and stall and the process begins again. If I DON’T clear the code it will idle until it starts to warm up
6 - as the car warms up, it is drivable and runs fairly well if I’m easy on the throttle. It also seems to be running very rich in this state. Hard throttle will result in bogging and sputtering.
7 - JUST before it gets nice and warm (optimal temperature) the car will start to sputter and want to stall again. If I’m driving at the time (ie. not stopped at a light) it will backfire a LOT. Flames out the back, the whole 9 yards. Seems like I’m running super rich / flooding.
8 - Pull off to the side of the road and let it idle for a little more to get nice and warm (still not clearing the code). During this time, if I feather the throttle, I can keep it running. But if I hit the gas hard, it sputters. Usually this occurs at 2000 RPM and above. I will also get misfire codes on all 4 cylinders. Lots of sputtering and misfiring at this point. The neighbours probably hate me.
9 - after 20-30 more minutes of idling, I can carry on it runs AWESOME. No issues at all. I can even clear the code at this point and it will NOT come back as long as the engine remains warm.
10 - On a really cold day, if I stop for say, 20-30 minutes, the engine temperature will end up just below the “sweet spot” and I’ll be at about step 7 above. And the process repeats.
I won’t get into the details yet, but for now, ignore the P0340 code. I’ve diagnosed this 6 ways to Sunday, replaced sensors, etc. I don’t think it’s the issue. Looking for other potential causes at this point.
Thanks for reading. Any suggestions would be appreciated.