P0303 Likely Causes...

[Stasi]

Hi, a code hitherto unknown on my 2.0 HPi popped up at the same time the car started running on three cylinders, and it is apparent that something is amiss, what i would hope for is almost a 'likeliest cause' and suggestions for eliminating things without having to buy components to substitute until the problem is cured..... the fault appeared whilst travelling at 80mph and was accompanied by the ESP/ASR fault and 'Anti-pollution faulty' followed by 'Anti-pollution inoperative and flashing engine symbol....

 

I will start the ball rolling by saying I would guess coil-pack as it was not accompanied by any mechanical noises or smoke etc, as one would expect if a major mech fault was the cause, and would not think that P0303 would be generated if the cause was low compression due to say a burnt or dropped valve....

 

Over to the more technically-minded now....thanks in advance for your input

 

Stasi

[paul.h]

An internet search on P0303 came back with this - misfire on cylinder 3, possible causes

 

Faulty spark plug or wire

Faulty coil (pack)

Faulty oxygen sensor(s)

Faulty fuel injector

Burned exhaust valve

Faulty catalytic converter(s)

Running out of fuel

Poor compression

Defective computer

 

So cheapest thing is to look at the spark plugs first.

[Randombloke]

This post might help for fault codes:

 

PSA fault codes

 

However as it was a sudden fault I'd look for a problem with coil pack, connectors or spark plug first.

[coastline taxis]

This post might help for fault codes:

 

PSA fault codes

 

However as it was a sudden fault I'd look for a problem with coil pack, connectors or spark plug first.

hi

Whats the year and engine code

[Stasi]

hi

Whats the year and engine code

 

 

Thanks Guys, will ttry the simple stuff first, it's a 2002 engine code is EW10D/RLZ

 

Regards

 

Stasi

[mlkey]

Thanks Guys, will ttry the simple stuff first, it's a 2002 engine code is EW10D/RLZ

 

Regards

 

Stasi

 

Good chance it will be the downstream (after the cat) O2 sensor. Can you feel the misfire when driving? If so, is it less noticeable or non existant when you start the car from cold, or accelerate under WOT (Wide Open Throttle)? During coldstart, and WOT, the downstream sensor is ignored (open loop), and the mixture is enriched.

 

If the sensor is giving a constantly high reading, it will cause the fuel to lean out, which in turn can lead to the misfire code.

 

Hope that helps.

[Stasi]

Hi Mikey, sadly it is a burnt piston and I'm trying to get a complete engine to get mobile again....

 

Stasi

 

 

 

 

Good chance it will be the downstream (after the cat) O2 sensor. Can you feel the misfire when driving? If so, is it less noticeable or non existant when you start the car from cold, or accelerate under WOT (Wide Open Throttle)? During coldstart, and WOT, the downstream sensor is ignored (open loop), and the mixture is enriched.

 

If the sensor is giving a constantly high reading, it will cause the fuel to lean out, which in turn can lead to the misfire code.

 

Hope that helps.