Mk3 Cavalier Owners Club | Vauxhall Cavalier Dot Com

Typical sequence: Hit a pothole and then have to brake sharply for an unexpected red light. As car comes to stop engine fades away and will not restart.
Quick fix: dive under bonnet and open relay box on near side. Remove rearmost module and wave about to cool it down for at least 2 minutes. Refit and car should start.
Long term fix: replace module.
Background: This module is the safety interlock for the high pressure fuel pump located near offside rear wheel. If car is in a collision or engine stops this module cuts off power to fuel pump.
It seems that this becomes oversensitive with time and typically needs replacing every 5 years.
Applies to 2 Ltr. SOC with multipoint petrol fuel injection. Could be generic to all fuel injection cars.
Module usually held in stock at major GM dealers.

Not all vehicles with 2.0 litre single cam (8 valve) engines have a relay box under the bonnet.

Although you will find such relay boxes on CD / CDX and Diplomat models where air condition has been factory fitted.

Admittedly most Diplomats came with the C20NE engine, auto transmission and air con.

Strangely, I have never heard of such an incidence previously.
It does not show in my copy of TIS' technical safety bulletins (TSBs)

That's strange because the first time it happened to us we rang the Vauxhall help line and they identified the cause straight a way. I am now on my third module so they last about 9 years. Cavalier does not have air con but is a 2 ltr CDi. Other module in the box is part of ABS braking system. I now carry a new spare in the glove box because the last time it tripped out it caused a major traffic jam!

My CD manual without air con has it too.
Not sure about the CD auto. It's in storage at the moment so I can't check.

Fuel relay is a tachometric relay, not impact sensitive. They do fail however.