Cam position sensor

[mwd]

96 OBW 2.2L MT, 126,000 miles. Sometimes won't start. Unplug cam position sensor and plug back in and it starts. CEL comes on then goes out after a few more OK starts. Code is P0340 (camshaft position sensor circuit failure). Assumed that it is the connector not making good contact and have worked on it to insure better contact, but have seen no improvement. This week it died when I hit a bump but restarted. It shows 2200 ohms across the sensor contacts. The connector reads 15K ohms from one contact to the other. Black wire shows 15K ohm to ground and the white wire shows 0.2 ohms to ground (other end connected to ECU). Sensor puts out voltage when engine is cranked.

 

Do the cam position sensors fail intermittently? Or does this sound like a wiring problem?

[camosuba]

Make sure that is really the problem I spent a day checking my GT legacy for what i thought was a timing belt problem and it turned out to be a dodgey wire on the fuel pump:banghead:

 

cam

[shaggy ant]

Hey check with the dealer there was a recall on the cam sensors of that vintage 2.2l motors. the real test is a bad sensor usually makes it hard to start after a hot soak such as coming out of the store and trying to start it.

[2X2KOB]

I'd replace it, and if that didn't fix it, I'd convince myself that I should be happy that I now had a spare, and keep looking.

 

I understand that this type of reasoning doesn't work for everyone.

[nipper]

96 OBW 2.2L MT, 126,000 miles. Sometimes won't start. Unplug cam position sensor and plug back in and it starts. CEL comes on then goes out after a few more OK starts. Code is P0340 (camshaft position sensor circuit failure). Assumed that it is the connector not making good contact and have worked on it to insure better contact, but have seen no improvement. This week it died when I hit a bump but restarted. It shows 2200 ohms across the sensor contacts. The connector reads 15K ohms from one contact to the other. Black wire shows 15K ohm to ground and the white wire shows 0.2 ohms to ground (other end connected to ECU). Sensor puts out voltage when engine is cranked.

 

Do the cam position sensors fail intermittently? Or does this sound like a wiring problem?

 

if its electrical it will fail intermittently. It sounds more like an electical pigtail issue. SInce you tried to make a better connection, i bet there is an internal break in the wire. Wiggle the wire the next time it happens, as it can be on either side of the connector. Try to wiggle only the sensor side, then the loom side.

 

The postion sensors are hall effect sensors. The sensor generates a heart beat when the engine is cranked. you need an analog meter to see this heartbeat. The beat is so low, that a digital gauge wont pick it up properly.

When using the analog meter you should see an AC signal, 1 pulse, then 2, then 3, then 4, then one . I suspect the pigtail is damaged to the sensor.

 

nipper

[mwd]

Replaced cam position sensor and now all is well. Starts every time for the past 3 weeks.

[seanski06]

i had the same thing wrong with my 96 impreza....but mine was the crankshaft sensor

[seanski06]

i had the same thing wrong with my 96 impreza....but mine was the crankshaft sensor

[hklaine]

i had the same thing wrong with my 96 impreza....but mine was the crankshaft sensor

 

Same here, so I replaced the crank sensor and the cam sensor. Figured they are of the same age and electrically/mechanically similar if not identical so the other was bound to fail eventually too.