Started my 2001 XK8 for the first time in over a month. We have had flooding here in the Baton Rouge area and traffic has been backed up and still raining all of the time, so I haven't taken it out for a ride.

Shortly after leaving home I get a message saying "Restricted Performance" and when I try to accelerate it stumbles a bit but then runs fine as long as I don't try to give it very much gas. I drove it over to my Indy Mechanic and he pulls codes and gets PO332 which he tells me is a bad NOC Sensor. He clears the code and we go inside to look it up on his computer. I make arrangements to bring it in next week. On the way home the "Restricted Performance" light goes off but there is still that little light with the image of the engine on the left side, but the car is now running perfectly normally, even under acceleration. Any thoughts on what is happening, and would it be harmful for me to drive the car in this condition? I also noticed that a rat had gotten under my hood, but didn't see anything chewed upon. Could the rat have had something to do with this. Yes, this is a small rat and he stole some cheese out of a mouse trap that I had. I got a rat trap on the way home with some nice fresh Kraft Extra Sharp Cheddar for him.
I'd appreciate any feedback. Thanks.

 

Was your battery being charged during the time the car was sitting? If not, that is likely the problem. The electronics of these cars require a strong battery.

 

I charged it twice, and it was fully charged on Sunday afternoon. I'll go and put the charger on again to see how much it takes to charge if fully again, but normally it would not drop off very much in just three or four days.

Update. Hooked up the charger and the battery is back to fully charged in about 10 minutes. Battery was in good shape.

 

Good, but you might have it load tested. Another possibility is a bad connection either in the power or ground circuits, but that's a lot more work and you might wait and see what your mechanic says.

 

In a word, Yes. The Rat could have, and probably did cause the whole thing. When the car goes into 'Restricted Performance' it will not exceed 3000 rpm, I believe, but the fact that it is intermittent and cleared while driving, makes me think that it did chew into the wires at some point along the sensors wiring, or at some component connected to the sensor that generated a code. I do not believe a 'Restricted Performance Alert', under normal circumstances, would clear itself while driving, and without a restart.

I would definitely be concerned with a Rat taking refuge in the Engine Bay, and would thoroughly investigate all of the wiring, including the wire wrapped in the black plastic wire wraps. It may not have pierced the plastic wire wrap itself, but may have damaged the wire within, and with the textured ridges it could be difficult to tell if it was breached.

Were you able to determine where it was nesting, i.e. any 'droppings' or urine pools, or do you have one of those 'black lights' to check for pet urine? Finding out exactly where he was hanging out may pinpoint the damaged area. Check the wiring and components, as they will chew on anything, in the two covered 'boxes' at each side under the hood next to the hood latches. This would be an ideal place for a Rodent to nest, and the passenger side has a cutout that a Rat would be able to enter and exit through. I have not checked the drivers side 'box' that closely, to see if there is a big enough cut-out in it to get through, but it does not take a big hole. They will also get into the cockpit to harvest the carpet padding for their nests.

One of my responsibilities at work was managing the Site GSA Vehicles, due to our small Staff we had to take on many 'Roles' in addition to our primary function. The Rodent problem was extensive, and they took a particular interest in the Heat Shielding on the O2 Sensors wire harnesses in-particular, of our new 'Fleet' of Oldsmobile Alero Service Vehicles, mostly only destroying any wiring with that type of Shielding, but I also found chewed-on wire cables as well. This would cause the dash to light up like a Christmas Tree and sometimes cause all sorts of intermittent drive-ability issues, and for me, a thirty+ mile drive into town to have it replaced, since we were not allowed to do the work ourselves.

These were small field mice, and they did allot of damage, not only to the GSA Vehicles, but to Staff vehicles as well, but the 'Company' paid for any Rodent damage that occurred to our vehicles. Plus, there is nothing quite like the look on someones face as they are driving down the road, at Seventy mph, and a mouse scurries up their pant leg.

 

Knock sensors and water are not compatible. Chances are you will need to replace the sensor. I did both ob my sensors on my 4.0 without removing the intake.

When your car goes into Restricted Performance it will restrict your engine from going over 2500 to 3000rpm. So not to panic it was operating properly just hope that all it is is a bad sensor.