CEL - bit weird, clearing stored fault?
 

Hi guys, I got a Check Engine Light showing the other day cruising on the motorway in 2000MY UK turbo classic. Pulled over, turned the engine off and on and the CEL cleared and did not return. After the journey I got under the dash and connected the two black and two green connectors together to get it to diagnose the fault. The CEL just stayed on with the ignition on (engine not started), I thought it should flash the relevant error code?

Anyway, I floored the throttle, raised it to halfway for 2 seconds then started the engine (as per some instructions I've got for 'test mode'). The CEL went out and stayed out. I then drove the car gently around the block a few times and after a few minutes it started to give the error code for oxygen sensor (3 long flashes, 2 short ones). I disconnected the connectors and have driven the car a few times since and the CEL has not returned, but the same error code shows up when I repeat the above procedure.

Now, does the fact the CEL doesn't come on mean there is no longer a fault? If so, how do I clear that code? Or does the fact that it is still showing that code in test mode means there is still a problem?

Also, my local dealer wants about £260 (+VAT?) for a Lambda sensor, if it is foobared can I get a sensor anywhere else for less?

Any help much appreciated.

oh ouch thats steep mate

For less money than that you could buy a wideband controller, sensor and gauge and then connect the narrowband output to the stock oxygen sensor signal wire. The Innovate LC-1 provides an analog narrowband simulation output that you can use.

WOW, that last post blew my mind a bit!

Can anyone actually clarify whether I have a problem to resolve!? Does the fact that the CEL has not come on since mean the fault has not reoccured? Or the fact that it still comes up in 'test mode' means the fault is still there? Cos I may not need a new sensor if the former is true!

Thanks for any input

If the CEL does not come on, then the fault has not re-occurred. The diagnostic mode will show you both stored and current code so you are likely seeing a stored code. You can reset the ECU by disconnecting the battery for a few minutes or by this method: http://www.scoobypedia.co.uk/index.p.../ECUReset#toc3

The method you have linked to is exactly what I'm doing but the error code is not clearing. I've tried it twice. So does that mean the error in the sensor is still there, even though the CEL does not come on in normal driving?

Try disconnecting the battery as well, if the same error is still returned after that, then for sure the oxygen sensor/circuit has a fault.

Cheers