Posted in the tec section, thought i try in here to.

I have the engine management light up on our 2002 focus 1.6se. I have done the dealer test mode on the dash and it is flashing “dtc none” I assume this means no codes stored in the ecu? Furthermore my diagnostics laptop (elm 323 interface) will not connect to the car (displays bus error) so cannot double check the codes, it works fine on our other cars, Alfa, Renault. The car seems to be running fine with no problems, idles well and pulls cleanly.

So am a bit stumped without a code to start with sad.gif . Any help would be greatly appreciated.

Posted in the tec section, thought i try in here to.

I have the engine management light up on our 2002 focus 1.6se. I have done the dealer test mode on the dash and it is flashing “dtc none” I assume this means no codes stored in the ecu? Furthermore my diagnostics laptop (elm 323 interface) will not connect to the car (displays bus error) so cannot double check the codes, it works fine on our other cars, Alfa, Renault. The car seems to be running fine with no problems, idles well and pulls cleanly.

So am a bit stumped without a code to start with sad.gif . Any help would be greatly appreciated.

Without a code read its impossible to say it could be any number of things. The dTC none on the dash test means nothing, that justs tests the instrument cluster it doesnt mean theres no codes on the ECU just that theres no codes relating to the instruments. Try rebooting the ECU (removing the battery for half an hour then reconnecting)

Thanks for the reply,

did an ecu reset and the light has now gone, how long it stays out is another question!

If there was a true fault I'd have expected it to come back on within the first minute of the engine running again. Sounds like it was just an ECU glitch, probably caused by a dodgy reading from a sensor somewhere.

Well 100 miles later and itsback on again, car is still running ok. Have Borrowed a mates code reader and got the code PO420 (catalytic converter bank 1 low efficiency) the light has been cleared again and has stayed out.

We need this car for a 500 mile round trip next week, what potential damage could prolonged driving cause with this fault?

Well 100 miles later and itsback on again, car is still running ok. Have Borrowed a mates code reader and got the code PO420 (catalytic converter bank 1 low efficiency) the light has been cleared again and has stayed out.

We need this car for a 500 mile round trip next week, what potential damage could prolonged driving cause with this fault?

does your mates code reader have a live data facility? this would allow you to compare the lambda sensors

does your mates code reader have a live data facility? this would allow you to compare the lambda sensors

No it was a hand held job that just read the codes.

Mine how ever dose but as yet will not talk to the car (see my first post). As/if/when I get it connected what sort of difference between the sensor readings am I looking for?

How do you diagnose whether it’s a faulty sensor or cat?

thanks.

Bump..