Iq3 -Cvt Fault Code P0842

[Passim]

Hi

My 2009 IQ3 with 42,000 miles on the clock presented me with an engine management light and flashing VSC off light and the VSC icon out of the blue one morning, after the vehicle had been parked for a few weeks. ODBii reports P0842 Transmission pressure sensor circuit A low.

The dealer I took it to does not seem to have a clue. The service manager is telling me that it is really a manual gearbox with an electric clutch, doesn't inspire confidence. Unfortunately there are only a handful of dealers and each is about 100 miles from me, so not simply a matter of taking it somewhere else.

Garage is recommending changing pressure sensor but they are not sure that it is the cure and suggest it could need an ECU as well. All in this could be £1,000.

Has anybody else come across this problem? The car drives well, there are no other incidations that there is a problem other than the dashboard lights.

If I have to replace the ECU I would want to source a second hand unit or a refurbished unit. The car isn't worth the £800+ that Toyota want for a new unit. I am not convinced that the garage are even looking at the correct part. I have a part number of 89661-74080, can anybody confirm this is the part I need, if it is the ECU or could there be another controller elsewhere on the car?

Hope someone can help!

Passim

[Soeley]

Time to find a new dealer or go to a local independent garage. The CVT (Constant Variable Transmission) is nothing like a manual gearbox with an electric clutch fitted! They don't have any gears as you would think https://www.youtube.com/watch?v=DldUaOWnKQM

In fact I'd go back and ask to see the service managers qualifications.

[craggle]

I'm never confident when someone suggests changing the ECU either. An ECU is very unlikely to go wrong without failing completely.

Maybe the oil pressure is low? I've looked at the manual and it mentions tons of checks you can do if you have a pressure gauge and the time to do it. Maybe it needs an oil change but 42k miles isn't very high.

The manual does state however that the error is either a faulty sensor (Short circuit), a faulty wiring loom or a faulty ECU. Maybe unplugging the sensor and starting the car will yield different results?

Craig.

[craggle]

Here is the position of the sensor, just remove the wheel and the plastic cover and it's right there.

Wonder if the connector is full of water?

Craig.

[Passim]

Craggle

Thanks for the manual extracts. First thing I checked was the plug to the sensor it was fine. The dealer says that they have checked the loom for damage/ shorts and say it is OK. They say that the sensor is returning voltage readings that are not correct so hopefully it is the sensor and it will only cost me a couple of hundred pounds or so.

I agree with you that ECU would be more likely to fail outright.

I assume they checked the oil level, in any case it was checked about 5000 miles ago and there are no obvious leaks.

Can you tell me from the manual that it is the main ECU that controls the transmission or is there another box tucked away somewhere?

Cheers

Passim

[Devon Aygo]

The ECU is the same box for both engine and transmission control you cannot however swap the ECU from another car as it is coded to car it is in and once coded it cannot be re-coded to another car

[Passim]

Thanks Devon Aygo, it is bad news but thanks all the same. I'll have to hope the new sensor cures the problem.

Cheers

Passim