Donīt know how to check neither, above my very rudimentary skills. I don't even know what you mean by cap and rotor... a car with electronic ignition has these? (now you know how clueless I am!)

From what you guys tell me, obviously I am very skeptic about it being the oxygen sensor. I am replacing it nevertheless (I should, right? as it can damage my cat and is hurting my engine behavior, efficiency).

Anything I can check quickly if car leaves me stranded again?

 

Well I have a feeling since it started again then it has spark....check Main Fuel Relay

If not we're just shooting in the dark, the EURO models could have some sort of system that we don't have...we don't get many members from over there

 

I know its very hard to really help me like this. Thanks for the replies nevertheless.

The car, when it didnīt want to start, had spark (and it cranked, and I heard the fuel pump pressurize, and all fuses where ok). If you have any ideas for next time, give it a shot so I can try it... but car now is running fine.

Thanks again!

 

If disconnecting the battery doesn't reset it then you will need the code reader. I'm just saying that didn't work on some other cars I've worked on, not that you do need one. Try disconnecting the battery first.

If your not sure the mechanic is telling you the truth just go to another mechanic for a second opinion. Don't tell him you've had it checked once already just tell him the light came on and you need it checked. If the second mechanic also says it's the O2 sensor then you're good. If he says it's something else, on to a third mechanic...

 

Main Fuel Relay

 

Is there any easy way I can check a relay? I know the basics of what a relay does... and how to use a voltmeter, ohm-meter (not sure of translation).

 

no o2 sensor or failing one you are gonna be running pig rich which could/will foul out plugs and create a no start situation. As far as resetting the ecu, if you disconnect the negative battery terminal for 30 minutes it will drain all the backup power to the ecu, you usually do this also when servicing airbags to be sure that the charge is completely gone. It is a hard reset and should clear anything found in the ECU which may inhibit the car from starting.

 

Thanks scooby and others for reply. The 30 mins tip is a good one. I have ordered the new sensor and will inspect plugs when I change it, see how badly they are (probably regardless of the sensor influence, its about time to change them nevertheless).

 

The fuel pump wouldn't prime if the main relay was out.

 

Yes it would

Main fuel relay prevents the injectors from firing