Focus Mk1 2002 Engine Management Light Problem

[GazM23]

Hi, Only joined the site today but I'm hoping you can offer me some much needed guidance here.

I bought my focus in March (2012), and after a couple of weeks suffered the annoying problem of the speed sensor failure, so the garage I bought it from kindly replaced the cluster and the speed sensor too. After a few more weeks the engine management light popped on, so took it to a couple of garages who tested it on a diagnostic machine showing the code 'Catalyst Efficiency Below Threshold', one garage immediately said they needed to change the CAT, but the second garage thought it only 'might possibly' be the CAT and so ran an emissions test on it. The car flew through the emissions test, and was told to run some Redex through it and get it serviced. The Engine Management light it still on and showing no signs of moving. The car runs totally fine, and every mechanic I take it to, hasn't the foggiest what it could be.

Ive read on another site that it could be a dodgy sensor??

Has anyone else come across anything like this or know what could be the solution for me please?

[Stoney871]

Try disconnecting the battery for 20 minutes to reset the ECU and then go for a good drive to recalibrate the system.

Make sure you have your radio code first though.

[DJ_Andy_M]

Hi, Only joined the site today but I'm hoping you can offer me some much needed guidance here.

I bought my focus in March (2012), and after a couple of weeks suffered the annoying problem of the speed sensor failure, so the garage I bought it from kindly replaced the cluster and the speed sensor too. After a few more weeks the engine management light popped on, so took it to a couple of garages who tested it on a diagnostic machine showing the code 'Catalyst Efficiency Below Threshold', one garage immediately said they needed to change the CAT, but the second garage thought it only 'might possibly' be the CAT and so ran an emissions test on it. The car flew through the emissions test, and was told to run some Redex through it and get it serviced. The Engine Management light it still on and showing no signs of moving. The car runs totally fine, and every mechanic I take it to, hasn't the foggiest what it could be.

Ive read on another site that it could be a dodgy sensor??

Has anyone else come across anything like this or know what could be the solution for me please?

Wouldn't it be ironic if it was my old 02 plate focus! I part-ex'd my focus estate around this time! That had the common focus speedo problem.

Read your other post about getting the codes cleared, and welcome! Post some pictures up of your car!

[GazM23]

Try disconnecting the battery for 20 minutes to reset the ECU and then go for a good drive to recalibrate the system.

Make sure you have your radio code first though.

Just tried this yesterday evening and took it for a good old drive. Thought it had done the trick but its just come back on. Would a faulty CAT still have pass the emissions test done a couple of weeks ago though? Any ideas where I should go from here?