OBD Codes

[Paul Fraser]

Hi, my OBD2 gives me P0300-0303 codes for a recent series of engine check lights in my European '97 2.5 manual 5 speed. The Renntech fault texts decoder gives 'Misfire, cylinder 1 damaging to TWC' for P0301 and similar for the others (cylinder 2 & 3 for 0302 & 0303), whereas the Renntech DME engine codes list gives 'Misfire Damaging to Catalytic Converter'. Are these the same and can anyone shed more light (unintentional pun) on this? What is TWC for a start?

The OPC says a new variocam is required but I'd like to understand what the fault is for my own education and amusement. Cheers.

[Loren]

TWC= Three Way Catalytic Converter.

These codes means that what is going on is damaging to the catalytic converter (flashing CEL) and the car should not be driven.

Potential causes for this are:

- wrong, fouled or faulty spark plugs

- bad spark plug connectors

- loose or broken spark coils

- valve lifters (if chattering)

- camshaft control (on that bank)

- Variocam not switching over properly

A scan tool should be connected looking for other codes. As well you should check to see if the adaptation values in area 1 differ in bank 1 and bank 2 (e.g. TRA=0.02/TRA2=0.27), the adaptation values for area 2 are generally normal.

[Paul Fraser]

Thanks for your reply. The CEL only flashes when the car is idleing/stationary (when it sounds a little rough/lumpy) but has never appeared when being driven; also it only seems to happen after being warmed up, not when cold: does this suggest any of the list below? I assume it is not the spark plugs, coils or connectors as all three are affected?

I'll have a search for scan tools on the site (I assume this is something different from the OBD2 I have).

[Paul Fraser]

The variocam wasn't switching over properly. New solenoid fitted at Ninemeister. £322 inc. VAT. They say it is a common problem with Boxsters (and I presume 996s, do they have the same variocam design?) and have done "hundreds", only once having to fit a new variocam (£1150) which is what the OPC does as a matter of course.

[kleinekabouter]

The variocam wasn't switching over properly. New solenoid fitted at Ninemeister. £322 inc. VAT. They say it is a common problem with Boxsters (and I presume 996s, do they have the same variocam design?) and have done "hundreds", only once having to fit a new variocam (£1150) which is what the OPC does as a matter of course.

I am getting the same P0300-P0303 error codes on my European MY1997 986 2.5 Tiptronic. I changed the spark plugs and also swapped the ignition coils from left to right, but the error codes kept coming back. I did not find any air leaks, I cleaned the MAF and measured the resistance on the O2 sensors, but they were identical so I excluded them from the list of possible causes.

After having found this thread I decided that an independent shop should take a look. They have narrowed it down to the Variocam solenoid, just like in this case. They want to remove the engine to be able to change the solenoid. Is engine removal a necessity for replacing the solenoid?

[RFM]

Hi

It is possible to change the solenoids with the engine in the car.