Mike Molloy

Poor old scoob ground to a halt at the side of the road the other night. Symptoms felt just like running out of fuel. Fault code raised was 32 (oxygen sensor).
Checked the wiring, and it seems the ECU turns on the fuel pump relay for a second or two after ignition on, but then turns it off.
Anybody know what failure would cause the ECU to cut the fuel but only return code 32?

scooby.steve555

iTrader: (5)

I may be wrong but I imagine the pump pressurises the system for a couple of seconds then won't start up again until you go to start the engine..

Someone confirm this?

Steve

boyward

Pretty sure that the pump just primes the system until you start the engine, gets the pressure up and then just sits static until pressure drops, same on virtually every car I'd suggest that it is nothing to worry about.

Oxygen sensor in exhaust is unrelated and probably knackered, probably just needs replacing, they do wear out as i'm pretty sure they're a catalytic sensor so once the catalyst begins to deteriorate/run out it will start to give incorrect readings and then the ECU incorrectly modify the air/fuel mixture entering the engine ... likely to over fuel and run rich.

Hope that helps.

AS Performance

iTrader: (4)

Lambda sensor will not stop the car running on its own, and as above the fuel pump only primes and then stops until the engine fires..............

would actually carry out a fuel pressure check in the first instance

Gambit

iTrader: (6)

i bet it its the relay in the sigma alarm for the fuel pump

Mike Molloy

And the prize goes to Gambit - it was the stupid Sigma M30 alarm *again*...
Thanks for the advice about the fuel pump operation.
The diagnosis would have been a lot easier if I had a correct wiring diagram. All the ones I found on the interwebz seem for be for US spec cars or LHD or something.
Anyone know if there is a 99MY UK Turbo RHD wiring diagram posted somewhere?