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1999 C2 996 low idle problem w/o AC on

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Hi, first post, but I have been lurking for some time.

I recently bought a MY99 C2 996, 6 speed man. The car idles within a normal range with the A/C on (around 600-700) but when I turned the A/C off the idle drops to 350-450 and the car feels like it is going to die. I spent a few hours cleaning out the TB and the ICV, but the problem is still here. On a side note I had a P0341 (CPS bank1) and P1397 (CPS bank2) engine light came on about 150miles after buying the car. I cleared the light about 50 miles ago and it hasnt returned, but im sure it will.

Any ideas, it's my daily driver to school and im broke now??

Also, my last car was an e46 bmw 325ci and it had the same problem it idled at 500 and 650 with the A/C on and I got a cam sensor code and replaced it, engine light never came back, but idle never changed!

Edited by usc e46
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P0341 Camshaft Position Sensor 1 - Signal Implausible, Short to Ground, Short to B+

P1397 Camshaft Position Sensor 2 - Signal Implausible, Short to Ground, Short to B+

Potential causes:

- No power supply.

- Short circuit to B+

- Short circuit to ground.

- CMP sensor faulty

Check the wiring...

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Thanks for the reply. I am new to working on Porsche cars; from what I have read: on sensor in in front and another in the the back of the motor. Where do you suggest I start looking in regards to wiring? Ive done a lot of work on bmw's but my knowledge about wiring is poor. Loren, do you have any engine and wiring digrams?



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The first faults say the DME is not getting a signal from either cam position sensor.

Now you are getting a fault that says it can't change the camshaft adjustment via actuator - this would seem logical to me.

If you don't feel comfortable tracking this down you should get the car to a shop that specializes in late model Porsche's and has a PST or PIWIS tester.

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I gave the car a 60k mile service and noticed one of two wires was off of some unit sticking out off the side of (verticle) cylinder #6 (anyone know what it is?) Anyways pluged the wire back in and the CEL stayed off for 200 miles... but the CPS bank1 and 2 lights returned.

Are these the hall sensors? Are they the same sensor on each bank? Im tired of this problem :angry:



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  • 3 weeks later...

For anyone wondering the current situation: I replaced the bank 1 hall sensor ( it can be done without removing the AOS, if you loosen it up and pull off the bellow) All lights have been out for about 500 Miles.

I bought both sensors and might as well replace the other one (bank 2- front of motor/ back of car) Anyone know the best way to approach this one? I tried from the bottom and couldnt get it with the given room.

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Did this fix the idle?

No, it still idles at around 600-610 with AC and 500 w/o AC

weird thing: My e46 bmw coupe had the same light after I bought it, I replaced the same sensor- same bank and it idled at 500 w/o AC... and 600 with the AC on-- strange. Sold it before I ever figured it out, ran fine for the 15,000 miles I put on it, just low idle.

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