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I have been getting an intermittant CEL I believe to be a Hall Sensor code on my wife's MY91 964 C4. Starts and seems to run fine.
Search here has been returned only vague information. Is there any danger in driving the car with this happening?
Any tips on what things I might check before taking it in to the shop?
The Hall Sensor code sometimes comes up from stray voltage in the system. Have you checked the rear for sparks at night? Open the rear in a dark place with the engine running. Look for sparks. Try spraying a *mist* of water over the wires and see if that generates sparks. This would indicate that your wires are old, dry and leaking voltage.
You can also check the ignition coils. If they are original they may be getting a bit long in the tooth. Pull each igniter (on the front of each coil) and try and start the engine. If either one fails to start the car this is an indicator that the coils need replacing. Though, you may still have a problem if this test shows nothing. Coils are funny. At ~$50 each it's a good investment, in my opinion, if they are original. If you do get a failed start you can try swapping the coil leads to be sure it's the coil and not downstream.
The Hall Sensor code sometimes comes up from stray voltage in the system. Have you checked the rear for sparks at night? Open the rear in a dark place with the engine running. Look for sparks. Try spraying a *mist* of water over the wires and see if that generates sparks. This would indicate that your wires are old, dry and leaking voltage.
You can also check the ignition coils. If they are original they may be getting a bit long in the tooth. Pull each igniter (on the front of each coil) and try and start the engine. If either one fails to start the car this is an indicator that the coils need replacing. Though, you may still have a problem if this test shows nothing. Coils are funny. At ~$50 each it's a good investment, in my opinion, if they are original. If you do get a failed start you can try swapping the coil leads to be sure it's the coil and not downstream.
Cheers,
Dave
Dave, thanks for you input.
Did some checks tonight.
AFAIK coils are original so might be worth changing them out as you mentioned.
Engine starts fine with either coil.
No sparks seen anywhere with or w/o H2O. Wires were all changed about 5 years ago and still look new.
All wires seated well in caps.
Reseated Hall sensor plug.
Now the CEL is off but it's done that before.
I guess well wait and see.
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