I Have A Mrk4 Opel Astra Which Has Started Doing Same As This Guys Astra, Only Prob Is It Does It Once A Day, Normally Once I Have Travelled About 10 Miles And The Engine Is Warm The Car Goes Into Limp Mode, Sometimes If Switched Of And Restarted It Sorts

[sapphirevalet]

i have a mrk4 opel astra which has started doing same as this guys astra, only prob is it does it once a day, normally once i have travelled about 10 miles and the engine is warm the car goes into limp mode, sometimes if switched of and restarted it sorts itself out for about 100yds before going back into limp mode, i have disconnected the temperature sensor on thermostat housing and reconnected it agian and occasionally this seems to rectify the problem and although the service light stays lit the car will rev ok and drive no problem but when driving it revs slightly higher than normal when changing gear, i am at my wits end with this problem and was wondering if anyone has some advice or probable reason as to the nature of the problem, many thanks....................

[tonyav]

It could be one of many things, it's most likely a sensor of some sort though. To know exactly where the trouble is though you will need to get your car plugged into a diagnostic code reader, everytime the engine management light comes on and the car goes into limp mode it will leave a fault code stored in the ECU which the diagnostic code reader will pick up.

[sapphirevalet]

yes but the magagement light will not come on at any point, its only the service light with car and spanner that comes on, i hav diagnostic tool and really wish the management light wld come on then i could poss get some sort of fault code, i have a suspicion it cld be something to do with the throttle position sensor, i have cleaned egr valve etc but havent changed any sensors yet..............

[tonyav]

If it were to be your throttle position sensor I think it would put the engine management light on.
However I have just remembered that I used to have a Vauxhall Calibra some years ago a 2.0 16 valve and that gave me some grief for a while by going into limp mode without the engine management light coming on, turned out to be the cam sensor playing up intermittently.

[sapphirevalet]

are you sure it was your cam sensor and not the crank sensor, as i have had a few people mention the crank sensor to me before now eh???

[tonyav]

Yes I'm sure it was the cam sensor, it was me that bought a new one and fitted it.
One of the symptoms of a dodgy crank sensor is the car being a bit difficult to start.

[Hopkirk]

Forget the EGR valve as a cause - mine was faulty on my Mk4 Opel Astra but the symptoms were completely different.

[ELVIS68]

When my Nissan Navarra went into limp mode, my mechanic suggested giving it a good hammering in each gear to 'clear it out', it's been fine since