Cooling fan on & Temp is -4 celcius

[nealgarfield]

Hi Everyone,

I've a 2005 3.2 Cayenne and owned it for a couple of years. :thumbup:

Recently, it's been doing some weird stuff. :(

Over the winter I've been getting the 4 wheel drive failure coming on and off. Basically. When I start the car, it can be hit & miss - once in 10 it will display the fault. Just switch off, switch on again and hey presto - the fault goes.

More recently though, I've had a few problems starting the car. Some mornings, I turn the key and the engine turns over but doesn't start. If I stop & try again, it starts okay but, after a short while (seconds), the cooling fan kicks in and doesn't stop until the ignitions switched off (it's the engine cooling fan not the a/c fan). This morning, the outside temp was -4c and the fan came in straight away. Oh, the temp gauge doesn't increase either - after a run of 15 minutes (5 miles in traffic) stays at 40 (bottom of the gauge).

Now, this happened a month or so ago when, the engine run really lumpy & stalled when the throttle was pressed. This problem persisted for a few days then went away (no fault stored in the memory, no engine management light!!!!! - No trace of what could be wrong).

My initial reaction is the temp sensor (throwing wrong readings to the engine management system and implying the engine's hot and weakening the mixture so bad starting).

Would you believe it though, after this fault's been on the car for the last 4 days or so (same as the last time as well), on the journey home, the engine cooling fan is working as normal and the temp gauge is back operational at normal temperature.

The only thing that's throwing me on the diagnosis is the other intermittent fault with the 4 wheel drive failure & on occasions, the PSM has said it had a fault. Could this be a CAN bus fault and a spike or perhaps in the need of an ECU update?

The only thing I'm aware of with the electrics is the fact I've had a tracker fitted (2 years since). Perhaps this is causing a problem with the electrics?

Anyone out there had similar issues?

Also, if it is the temp sensor. Anyone fitted one to the 3.2 engine - do you have to take the gearbox out to get to the thermostat housing like the workshop manual suggests? Gearbox removal for a thermostat? Whatever next! :cursing:

Any help is appreciated. :cheers:

[wvicary]

The temp sensor has been updated to a newer part number which can cause the starting issue and the coolant fan issue. Be sure to replace the o-ring seal and the plastic retaining clip that holds the sensor into the coolant flange. You don't have to remove gearbox but the sensor isn't nice to reach unless you have the same size hands as a 7 seven year old french girl. It's located in a coolant flange at the rear of the engine on the left side. You will loose approx 1L of coolant so have some replacement on hand.

[nealgarfield]

Thanks for the info.

Is this the one on the thermostat housing or the one on the coolant gallery / rail?

Do you know the new part number at all (I think the one on the coolant rail is a 996 no. (oil temp on the 996?) whereas the thermostat one is a 995 no.

Thanks.

[cayenne69]

Hello, I have rough idle from 30 secs to 2 mins after start the car and longer when cold. So I suspect the coolant temperature sensor because coil packs and spark plugs are new on my v6 3.2 2004. I'm searching for this problem since I have the car... Do you have any tips to test the CTS with durametric or to replace the part. Thanks.