Last night as I was pulling in to my garage after a ~20 mile cruise the following warnings flashed on the dic: service traction control, service active handling, reduced engine power. My accesory belt, which has been squealing intermitently (low volume squeal at anything over 2k rpm when it's doing it) is now seriously frayed all along the edge that faces the rear of the car. It does not appear to have jumped off any pulleys, is still centered and doesn't feel loose. I have an underdrive pulley, btw. Water temp was at 220/f when this happened, accesories all work normally and I can find nothing else unusual in the engine bay. Obviously the belt need to be replaced and my questions are as follows:

1) What (other than overheating) can trigger reduced engine power mode? That one still comes on every time I insert the key, engine running or not.

2) Is the active handling system driven off one of the the pulleys down there? If so which one? If the active handling problem is not related to the frayed accessory belt what else should i be looking for to fix/replace? It's Sunday night and car is out of warranty anyway so I'm on my own for now.

Here are the current codes I get:
P0160 - heated oxygen sensor, circuit high voltage bank 2 sensor 2
P1220, P1221 - TP sensor 2 circuit A, TP sensors 1/2 performance

I should also mention I have gutted cats and therefore o2 simulators, not o2 sensors. Seems unlikely that all this stuff would go south exactly the same moment by pure coincidence but i don't see how it could all be due to a frayed belt.

Thanks.

 

A frayed belt is usually caused by the pulley starting to back out. Is your A/C belt still in place and not frayed? Usually the A/C belt will go first, followed by that other belt.

Active handling is not driven from a pulley directly.

 

Multiple error messages on my 99 A4 (I've got an '00 MN6 now) were caused by low/fluctuating system voltages as the battery slowly died. If one pulley belt has failed maybe the alternator drive is slipping too?

You may want to check the system voltage and/or the alternator.

Good luck.