Thread: Recurring PO102 and PO443 in a '99 GP GT, 3800 series II, non supercharged

po443 is a evap code, the maf, have you checked the wires to the maf plug, if they are cracked or missing insulation the wires get whats knows as dry wire, and can throw the same code as a bad maf. new pig tails are about 10 bucks new.

I would like to share a scenario that turned out to be a good reminder/lesson of checking the simple stuff first when troubleshooting an issue with your car.

Along with the Jeep Liberty that my wife drives. My DD is a 2004 Pontiac Grand Prix 3.8L Non-SC with 168,000 miles on it. About 4 weeks ago, the Grand Prix came up with a CEL light. This was at the same time I was also dealing with the "Jeep Liberty - No Crank" condition. I was pre-occupied with getting the Jeep up and running. I ignored the CEL on my Pontiac.

The symptoms of the Pontiac were hesitation, pinging/detonation, hard time starting and occasionally stalling. I get the car scanned and the stored codes are P0102 and P0443. Which points back to a failed MAF sensor and a leaky EVAP component.

Figuring I had a bad gas cap. It's replaced with an aftermarket cap. I also pull of the MAF and clean it with some MAF cleaner. Theres no change. Codes are still persistent and still runs like crap.

Assuming the MAF is bad. I go ahead and replace it and I also remove the throttle body and clean all of the carbon buildup from it. Although the throttle response is better. The root issue is still there.

So now I'm kinda at a loss of what it could be, Figuring I have a rogue vacuum leak somewhere and the car is sucking air . I spray carb cleaner trying to find the leak. No leak can be found.

Now I'm completely discouraged not knowing where to look next. So I go to Google and do a search on the 2 codes and some of the results lead me to a Grand Prix forum where I discover that these 2 components are on the same electrical circuit and if the fuse is blown it will generate the resulting codes.

I go out once to the car and open up the panel and what do I find?

The 10 AMP fuse is inserted halfway into the slot and it just barely in there. I began to laugh when I realized what had happened.

When I was beginning the trouble shooting process of my wife's Jeep. One of the first thing's I did was to swap battery's. The battery for the Grand Prix is located behind the passenger headlight and in front of the fuse panel.

The battery is a tight fit, so much that when your installing it, You need to have the fuse panel open and bring the battery in at a 60* angle to get it in. Even with all of that, it's still a tight fit.

So what happened was when I was swapping battery's, The corner of the battery must have caught the fuse and knocked it out of place.

While I was still in flashback mode upon seeing the fuse., I remembered when I tested my wife's battery in my car, That my car was hard to start and immediately registered the CEL. It never dawned on me to check the fuse, since I was so consumed on what was wrong with my wifes Jeep.

So long story short, I reinserted the fuse and cleared the CEL and the car is now running absolutely awesome with the new MAF and clean throttle body.

Hope this helps everyone, that when your troubleshooting a problem. Don't forget to start with the small first.