[PPP]

My turn to contribute to this saga and irritating fault code. Background is the car was first registered April 2000, 90,000 miles and was running without fault before the problem arose. It's a 986 Boxster S.

The symptoms are as listed by other owners on lots of forums - erratic idle and not revving above 2000 rpm. The code can be cleared while the car is running or before starting and then it will run perfectly but on a restart the code is triggered again and the rough running resumes. There is only one fault code which is P1502 DVE spring test fail. I have taken the following steps which made no difference:

Replaced the throttle body with one from a perfectly running car.

Cleaned connections and checked for air leaks.

Rapid switching on and off of the ignition.

Left the car with the battery disconnected for 24 hours and tried the adaptation process.

Ensured the battery is fully charged and holding charge.

Changed the fuel relay to a known good one.

I don't think the adaptation process is working. When I switch on the ignition I can feel a single distinct click from the throttle body but I don't hear any humming or other noise, however long I leave the ignition on for without starting.

This makes me think the code is correct and the spring test is failed but since it's repeated with a working replacement throttle body it cannot be mechanical but is more likely to be signal based. I'm obviously reassured it cannot be a serious issue as the car runs perfectly with the code cleared.

I now want to swap the DME and find it's bolted in with two normal 10mm nuts and five unusual splined nuts. Can anyone tell me what tool I need for these splined nuts as there doesn't appear to be enough space around all of them to get a socket on?