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Dave Nova
Dave Nova, GMC Technician
Category: GM
Satisfied Customers: 19450
Experience:  ASE Master Certification. GM World Class Certification
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2003 GMC safari van: cylinder..the exhaust)..removing..Drives fine

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I have a 2003 GMC safari van, rear wheel drive, 4.3 6 cylinder. I Just replaced the Cat(Fell apart and plugged the exhaust), down stream O2(Threads got damaged when removing), and the Cam shaft sensor. The van starts good, Drives fine, and does not miss fire. There is a P0016 code that keeps comeing up what do you suggest
Start by removing the distributor cap. Grasp the distributor rotor and attempt to turn the rotor. Does the rotor turn on the distributor shaft? Note: the entire shaft may move some, this is okay. The rotor should not move separately of the shaft. Let me know what you find.
Customer: replied 6 years ago.
The rotor is screwed on tight an moves with the ditributor. I checked that already and double checked it when I replace the cam sensor in the distributor. There is a small sensor with a 13mm bolt going threw it (its a two wire) on the back of the motor by the oil pressure sensor if i unplug it the same P0016 show up right away would that have something to do with it?

Is this sensor the Knock Sensor? Refer to picture below.



Customer: replied 6 years ago.
yes sir thats the it when it is unplugged the P0016 comes up right away could that be causing the code to come up unger normal driving conditons or is it not a factor? this is a company vehicle and i can not order any parts without proper diagnostics/approval.
The knock sensor will not directly set the P0016 trouble code. The knock sensor causes the computer to retard ignition timing. Do you have a scan tool capable of reading live engine data?
Customer: replied 6 years ago.
No I do not. I got one of those shit auto zone scanners that reads codes and erases codes thats it.

Has the distributor been removed from the engine?

Customer: replied 6 years ago.

No the ditributer has never been removed. The image that you sent me is different than the motor i have. I beleive the knock sensor is typical located on the LH head right?and i have a two wire sensor in that spot between the back two plugs, I do have a two wire sensor in the same loction as the knock sensor in your image but there is a bolt threw the center of it and the connection is pointing towards the center of the van. Also the oil fill tube is in the LH valve cover not the RH like in your picture.

This is still the knock sensor location. There are two different types of knock sensors used. The older trucks used a single wire knock sensor that screwed into the block down low near the oil pan. The sensor in the head is a coolant temp sensor. The distributor can only be installed in one position on the 4.3 engine because of the way the hold down is designed. I had run into this problem once before with this code. The distributor was worn, which threw off the reading from the distributor and there is no adjustment available. On that particular vehicle, I slotted the distributor hold down to be able to move the distributor. Since you do not have a scan tool that can read data, I can't tell you which direction to move the distributor. I would suggest replacing the distributor with a new one.
Customer: replied 6 years ago.

That sounds like it would do the trick. One final question I got I just drove the van with the dog house off and intermitantly under a load a slow speeds like leaving a stop sign the coil wire was arking to the block would that have a factor in this problem?

The coil wire arcing will cause a misfire, but will not have an effect on the P0016 code. You should replace the coil wire anyways, but that will not fix the P0016 code.
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