Thread: P0340 code
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Old 11-14-2017, 05:56 PM   #1
Jon Boy
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Join Date: Jul 2007
Location: Utah
Posts: 177

2001 SC2
Default P0340 code

Yesterday on the way to work, my '01 SC2 started running rough and flashing the SES light. I managed to limp to work and used a scan tool to check the codes. It said there was a P0300 and P0341. I got it towed home and started going through the diagnostic flowchart here.

I checked the plugs, and they were looking pretty bad—the gap on one of them was about .072. The resistance on the plug wires was a little low too, so I replaced both the plugs and the wires. I did a little test drive around the block, and it seemed to be running fine again. I went to go to work, and suddenly it was running rough and flashing the SES again. This time it says it's a P0340.

I've checked the plug wires and towers for corrosion, and everything looked good. I checked the resistance from wire 1 to wire 4 and wire 2 to wire 3, and I also checked the resistance on each wire individually and on each coil pack. Everything is within spec. I also checked for arcing and didn't see any.

I backprobed circuit 633 at the PCM, and it was at 4.95 both with the ignition on and the engine on. I also checked the voltage on that circuit at the ICM end, and it was the same.

Everything seems to be connected securely—each plug clicked on each end when I plugged it in. The wiring order at the coil packs is 4-1-2-3.

As far as I can tell, I've been all the way through the diagnostic flowchart, and everything checks out. But it's still running like crap, spewing really rich exhaust, and throwing a P0340 code.

I'm kind of at my wit's end. Where do I go from here?


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