check engine light on then off

[Joel96]

Has anyone ever had the check engine light come on for a few days then go off for a few days then come back on again? This has been the cycle on my 9/3 Saab for the past 2 weeks. every time I get a chance to investigate the light it goes off, then in about 2 days it comes back on. Everything is working fine in the car, I just can't figure out the engine light coming on and off. Any advice is greatly appreciated. Thanks, Joel

[chromatic]

Perhaps something is marginal and intermittently exceeding parameter limits. Try putting an OBDII scanner on it and getting a code out of it and that should point you in the direction of the problem.

[lotso99]

This has happened to me about 4 times now and when I bring it to Auto Zone to have the code checked it is the oxygen sensor. Just last week my light came on (I had almost no gas if that matters), I filled the tank, and when it got to a 1/2 tank a few days later the light went off.

[supercoupe91]

I had an intermittent- turned out to be the DIC slowly going bad. Eventually it turned into a hard failure. If possible, run diagnostics at your local parts store when the light is on.

[lurkydismal]

Just went through that with my Viggen, it was a bad thermostat.

[Joel96]

Originally Posted by lurkydismal

Just went through that with my Viggen, it was a bad thermostat.

The light was on today when I came home, if the light is still on tomorrow I will go to advance auto parts or autozone down here and have them check for codes. Can theses auto stores run a thorough diagnostic, do they have the equipment to run a complete diagnostic? I thought you needed a tech II for this? Thanks for the info. Joel

[Joel96]

Originally Posted by Joel96

The light was on today when I came home, if the light is still on tomorrow I will go to advance auto parts or autozone down here and have them check for codes. Can theses auto stores run a thorough diagnostic, do they have the equipment to run a complete diagnostic? I thought you needed a tech II for this? Thanks for the info. Joel

OK here is the code for my check engine light. P0340 this says cam sensor position. Does anyone know if this is serious? The light continues to come and go not sure what is going on. What does the cam sensor position code mean and how do I correct it? Thanks, Joel

[TheCommissar]

iirc the sensor is at the driver side (US) end of the cam closest to the cabin. Wherever it is, I'd check that it is clean and well connected (wires to plugs and plugs to each other) before throwing replacement parts at it. It could be the sensor but try the cheap/easy fix first...