Most puzzling case! 1998- 406 Diesel

[PrincePhilip]

I have a workhorse of a vehicle – a 1.9 406 estate. Four the past couple of years, when I start the engine, it starts fine but the rev counter stays in zero and engine runs rough and lacks power. I then turn off the engine or just almost turn it off, this action brings the rev counter to life and the engine adjusts itself and runs smoothly and I am on my way. I took to the authorised dealer and did a computerised diagnostic test. It came back a list of items- injectors, fuel pump, and some other things. All nonsense because the car functions very well. I have replaced the rev counter. Taken to couple of other computerised diagnostic places, but no one has been able to pinpoint the cause. To repeat, it starts fine, but 4 out of 5 times the engine stays unadjusted and rev counter on zero. The remedy is to turn the key a bit as if turning the engine off but turn it back before the engine turns off. This action adjusts the engine. Anyone had this problem? What is the possible cause?

[steve_earwig]

Hi there. I'm fairly new to these cars myself but that's definitely a wierd one. It strikes me that it could be the ignition switch itself - I'm not sure how many contacts are in use when the key is in the run position but it could be a contact isn't quite making it.

[mbell666]

i'd go for a wiring problem (bad contact, snapped wire) or ECU fault.

Afraid can't be much more help thou

[lisalax]

hi there, i hope you're still there. did you manage to get an answer to this problem. i've suddenly got exactly the same thing. thanks lisa.