sweet35th

Wifes Cayenne tripped this code yesterday (p0332), display said reduced power mode. She cycled key and normal operation returned. I cleared code today and will monitor to see if it returns. My question is, do these engines have a common issue with knock sensors? It appears as if you have to remove intake manifold to replace, not a big deal, but is there anything else I should replace if/when I have it off?

deilenberger

This would be the first I've heard of a 958 having a knock sensor problem - but certainly not impossible.... You didn't mention what engine is in your Cayenne so it's hard to say if there is anything else you should address while things are apart.

sweet35th

It's an S with the 4.8L.

deilenberger

OK - so if you have the intake manifold off - it would be worthwhile to take a really careful look at the three pipes that go into the thermostat housing (behind the water pump). One out the rear is known to leak, perhaps someone with more knowledge can speak on that one.. the two out the front are glued in, and have been known to work their way out of the housing, causing a massive coolant leak. There are two possible fixes - fix the existing ones by either epoxy them in place, or epoxy them in place with set-screws installed through the housing casting to make certain they can never come out OR replace the housing with the current style one - where the pipes are bolted to the housing. The second option costs more $$ and is more work since the water pump has to come out, the thermostat has to come out and gaskets and such will require replacement.

There is also a glued in hose fitting on the crossover coolant manifold behind the heads - below the high-pressure fuel pump (right side of the engine facing it, AKA port side..) That one is the same thing - except it's really hard to replace the manifold without engine removal (which is what a dealer will do..) One can drill/tap the housing to take a custom fitting (check the DIY section), or other people have drilled and tapped the manifold so a set screw can be installed locking it in place. Slathering around some epoxy like JB Weld isn't a bad idea either.

You might also check your intake valves for coking - deposits on the rear of the valve. Shouldn't be a big issue on a normally-aspirated one - but it has been seen on various Cayennes since they went to direct injection. If you see significant coking, take a few pictures and post them here and I'll try to find the posts relating to this possible issue.

Whatever you end up doing - take LOTS of pictures - and consider doing a DIY for the rest of us to see.

Hang Yu Xu

Does it solve the problem of reduced engine power after you replaced knock sensor? Thanks,