A little background:

I bought this 2006 Forester AT X about 4 years ago with a spun rod bearing. I've successfully rebuilt a good number (5-6 maybe) Subie 2.5s. I tore it all down and then, for circumstances I won't bore you with, it ended up sitting until just recently when I finally got it put back together.

So, I tried to start it finally, and it would crank and crank but not start. Not even thinking of hitting, just cranked. I hooked up reader and got P0340 - Camshaft Position Sensor Circuit Malfunction. I checked connections, etc. Disconnected battery to clear codes, reconnected battery, verified no codes, and cranked again. Have to crank about 30 seconds until CEL came on. Checked again - P0340.

1. - Checked sensor with ohmmeter - about 2K
2. - traced connectivity of sensor all the way to back of huge connector at back of engine
3. - Swapped in another sensor and tried - P0340
4. - Pulled the carpet up and eyeballed ECM for rodent damage, etc. - looks good
5. - Verified that I had put correct cam sprocket on that side (I have bunch of parts around)
6. - Measured resistance to ground from each side of the CPS sensor plug - got 24K on one and 0.8 ohms on the other,

Nothing.

As far as timing belt being off: I am not infallible, but I've done quite a few and never missed one yet. I really don't think that's it.

 

Would anything else cause it to throw this code? I originally thought maybe it was just old gas until I consistently got the P0340 code. Stale gas couldn't cause it to throw a P0340 could it? What would be the chances of a bad ECM?

Thanks in advance for any help,
Wally

Is the left side cam sprocket the same one that came with the car?  Crank sprocket the same ?  The cam sensor you put in to try , came out of a running car ?

Is the left side cam sprocket the same one that came with the car?  Crank sprocket the same ?  The cam sensor you put in to try , came out of a running car ?

 

Yes. Not sure! Yes.

 

As I said, I have a bunch of parts laying around - AND things got all mixed around during a move (part of the circumstances mentioned). While I could ID the cam sprocket, I ASSUMED ALL CRANK SPROCKETS WERE THE SAME! All of the other ones are from 2000-2002 Outbacks. I just checked on parts.subaru.com (they have great pictures) AND THEY ARE CRAZY DIFFERENT!

 

MT, I think you might be on to something!

 

I obviously need to check and make sure I have the right crank sprocket on, but - would the wrong crank sprocket cause it to throw a P0340? I guess I could see some logic where it can't accurately determine where the crank is and would, but I don't know those details...

 

Thanks! Going to go look at the other crank sprockets I have out there and see if one looks like the one that should be on there.

I found the crank sprocket that should be on there. And, even though I am 90% sure I shouldn't have another one of these, I tore into it enough to verify that THE WRONG CRANK SPROCKET IS ON THERE! Not even close! I've never been so happy to uncover a mistake!

 

Still curious what the logic is that would cause it to throw a P0340, but it obviously isn't going to run with the wrong crank sprocket.

 

Look how different:

 

One that should be on there:

 

http://parts.subaru.com/images/uploads/(101)%20parts.subaru.com/fullsize/a_20150810_1415324631.png

 

(wrong) one that's on there now:

 

http://parts.subaru.com/images/uploads/SimplePart%20-%20Subaru/fullsize/a_20160712_1446595524.png

 

MT Tom, I owe you a beer!

 

Thanks,

Wally

those are the crank triggers for the crank sensor.  you're cam and crank sensor readings were not lining up, giving you a code.

 

in terms of how many triggers there are per crank sprocket - there are two different styles.

Yeah, mulled it over way too much overnight, but realized I was overthinking it. With the crank triggers being so crazy different, it just couldn't make any sense of where the cam should be. So, it picks one to be wrong - in this case the cam sensor circuit.

 

Thanks,

Wally