Hi all.

I'm new on here apparently, as my old account doesn't seem to work anymore!

But here goes...

I Recently bought a 2001 Pre Facelift (Y plate), 2.0 ESP Zetec Focus.

It had 100k on when purchased.

Now the Engine managment light came on after 500 miles or so, which I had the code read and it was a P0420 (P0420 Catalyst System Efficiency Below Threshold (Bank 1)).

I reset this and all was well.

This then came back up - All the time, the car idling ever so slightly low, near on cutting out coming up to junctions etc etc..

I read and reset the code again and had no problem for a while, though it was still running groggy, idling low, and also taking a while to start from cold.

The light then came back on, which i just left it - 250 miles on, its just switched back off.

The car still takes a good while to start in the mornings, and occasionally the revs drop nearing junctions etc, the battery light comes on - but other times the revs randomly stay up at 1500 or so...

Also, since all this has been going on, the speedo and rev counter have dropped to 0 and come back once or twice, and since then, the speedo alone has dropped, all the odometer went to ---- with no numbers, The traction control light came on and stayed on (The button had no effect), and all stayed like it until restarted, the speedo has also just dropped alone and come back after a few seconds.

Its had a small vacuum pipe replaced as it was split, which slightly improved the idle, but no drastic difference...

Has anyone else ever had a problem like this?

I've been pointed towards the speed sensor, but have read that it can be various other problems too - I'm going to read fault codes again, and reset them tomorrow, but otherwise, I'm stuck!

Any help much appreciated

David

Sounds like you have a couple of problems mate. Firstly the management light is likely an oxygen sensor (Lamda) failing. The idle/revs sticking problem is likely to be the Idle Control Valve and finally, the speedo loss is Vehicle Speed Sensor. The VSS doesnt always log a code as it gives an intermittent fault not a permanent one. When it goes altogether the engine will cut out altogether. This happened on my ex wifes a few years ago. Thing was she was doing 50 coming off the M25. Car died, lorry behind couldnt react quickly enough and smashed into the back end writing the car off.

Balls to it...

Damn it..

I suppose Llambda would make sense, though the readings before and after the Cat were the same on the diagnostic, leading me to think Cat?

Speed sensor can stay until it gets worse then lol the worst it'll do is take some miles off the car :)

Could the idle control valve be clogged, so i can clean it, and where is it?

Cheers :)

I'm not an expert on the petrols but apparently its a simple job but cleaning only usually cures it for a while. In the long run its better to replace it.

As for the oxygen sensors I believe theres 2 one pre cat one after the cat. If ones giving a false reading you would think it was the cat at fault.

Ah fair enough, might pay to get some of those later on then, sort myself out with some cash when i start my new job and go from there :)

Cheers mate