My car threw the following codes: P0302, P0303, and P0340. I was running along at 40-60mph, not starting or revving or anything. The P0340 code indicates the crankshaft position sensor, so I checked it. The resistance between the two sensor pins was perfectly in spec (2K ohms). In fact, I bought a new sensor and the resistance was identical. I cleared the codes and after idling for ~30 seconds the problem came back. Sometimes the problem showed up as just the P030x (cylinder x misfire) codes and sometimes it showed up as P0340 along with P0302 and P0303.

I'm having trouble following the service manual description for the P030x misfires. Specifically, the point where it says "Check output signal from ECM". I checked the voltage drop between connector B137, pin 1 and ground and got 0V. I checked the other cylinders (connector B136, pins 4-6) and got 0V as well. The ignition switch was ON, so I know there should have been power. However I don't think I measured correctly because with 0V it seems like the car wouldn't run at all. The car does run, just very roughly like it's misfiring. I measured the voltage at the connector pin itself and at the ECM, and neither one gave me any voltage for these pins.

Can anyone help me correct how I'm following the service manual? Is there a common cause that people usually see with the P0340 and P030x codes that's not the sensor itself. My car has 21K miles.

 

No ideas? Anyone?

 

None at all and I am now getting that same code and I have about 66k on mine.. and no one seems to know anything about this.. I have to take it into the dealer and have them figure it out. I hate doing that because it will probably be an easy fix.

 

None at all and I am now getting that same code and I have about 66k on mine.. and no one seems to know anything about this.. I have to take it into the dealer and have them figure it out. I hate doing that because it will probably be an easy fix.

 

I had a similar problem recently got it fixed and it was due to a ground wire. First check to see if its a thing that happens and goes. When you get the codes are they all triggered all at once? If yes it has to be a ground wire somewhere. Good Luck. BTW is the CEL blinking and then stays solid?

 

FYI, here's what my problem ended up being:
1. Timing belt tensioner went out and the timing belt had a small tear. These things threw off the timing so that I kept getting misfires.
2. Head gasket was blown, kind of. I say "kind of" because I don't believe that the headgasket really needed replaced on its own. The shop doing the work (DBTuned) said that it had a little bit of coolant/foam in the oil, but not nearly as much as usually occurs with a blown headgasket. This may have complicated the matter, or it may have just been some unnecessary work that was performed to get to the root of the problem.