2003 GMC Sierra ENGINE WARNING LIGHT

RAMON MEDINA

MEMBER
2003 GMC SIERRA

2003 GMC Sierra V8 93.000 miles

MY CHECK ENGINE LIGHT CAME ON AND CHECKING DTC'S CODE IT GIVES CODE PO337 & PO332 (KNOCK SENSOR LOW VOLTAGE). I REPLACED BOTH KNOCK SENSORS AND LIGHT RETURNED. I REPLACED THE WIRE HARDNESS TO THE KNOCK SENSORS & CLEARED CODE AND AFTER TWO DAYS OF DRIVING THE LIGHT RETURNED. I ALSO USED GAS TREATMENT TO CLEAN THE ENGINE, RESET CODES AND NO LUCK, THE LIGHT RETURNED. IT APPEARS THAT MY TRUCK RUNS FINE BUT I'M CONCERN IF POSSIBLE ENGINE PROBLEMS WILL RESULT IF I DON'T FIX MY PROBLEM. I'M VERY FRUSTRATED AND DON'T KNOW WHAT TO DO NEXT IN RESOVING THIS PROBLEM. CAN GUYS HELP ME WITH THIS PROBLEM!

7 Replies

BLACKOP555

MECHANIC
10,371 POSTS

Do you notice the vehicle to be knocking when your going up a hill or something, or on heavy acceleration?

Wont cause damage if theres nothing pinging or knocking going on. If you want I can help you figure out if you can fix it or if it may be a computer related issue.

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Thursday, August 26th, 2010 AT 11:49 PM

RAMON MEDINA

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I would appreciated if you can tell me how to correct the problem. The warning light drives me crazy and also if i'm in long trip I don't know if something else goes wrong because the warning light is already on. I think that I can heard some pinging when full accelaration or when towing my pop-up trailer.

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Friday, August 27th, 2010 AT 10:02 AM

BLACKOP555

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P0337 Crankshaft Position Sensor A Circuit Low Input
and p0332 is for knock sensor low bank 2.

There is a technical service bullet out for your year and model of vehicle.

This condition may be the result of corrosion of the rear bank knock sensor due to water intrusion into the sensor cavity. This condition is more apparent on vehicles in which customers frequently wash the engine compartment

the knock sensor is in the rear of the block located under the intake manifold. Manifold will have to be taken off and then knock sensor can be checked to see if the corrosion caused it. If so the sensor will have to be replaced. Upon replacment you will have to use rtv sealant and build up a wall on the sensor to prevent water from gettin back on it go 1/2 inch wide bead and 1/4 of an inch high in a circle shape around where the knock sensor is at.

Check this first as it can cause your p0337 code.

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Friday, August 27th, 2010 AT 8:49 PM

BLACKOP555

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Note. When you removed the old sensors did you notice any fluid in the rear knock sensor cavity or not if so would be checking the new one to verify that its not soaked with liquid either.

Next that p0337 can cause engine misfiring causing the knock sensor to read faulty when it really isnt. Best bet is to check the voltage of the crankshaft pposition sensor with vehicle running by back probing the harness with a dmm. Let me know what AC VOLTAGE it is putting off. Important multi meter is set to AC not DC volts.

Next with vehicle off and sensor unplugged measure the resistance across the two wires going to the crank position sensor.

Also have you noticed extended cranking times

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Friday, August 27th, 2010 AT 8:57 PM

RAMON MEDINA

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When the rear sensor was replaced it was rusty and I had a mechanic replaced both sensors. I removed the monifold and rechecked for water damage and a saw a dry spots of water. I put a sealent around it like you suggested to avoid water. As for know a have no problems starting the truck and its running o.K.

I did the test you recommended on the voltage of the sensor hardness with engine running and I got.3 volts. Checking the resistance unpugged with car off 191.1 ohms.