helping my stepdad with his merc (avant gaurd diesel estate). the ecu light has been on and off recently. got the code read and it says no 4 fuel injector. would you immediately replace this injector or would redex help? is it like on the coupe where you can feel them tick/pulse to see if they are working correctly?

thanks

While it is technically possible, it's *extremely* difficult to tell whether an injector pintle is sticking by analysis of the signal waveform. I don't know of any ECU that can do this.

It's far more likely that the ECU is simply looking for open or short circuit on the driver coil (open is the more likely) and in that case redex won't help at all.

I'd switch injector #4 with one of the others and see if the error moves with the injector or remains on #4. That way you can rule out wiring or the ECU injector driver as the fault at least.

If the error follows #4 to it's new position then replace it.

thanks both will take a look at it next weekend and switch the injector around see what the ecu says