Engine Warning Light Loss of power

[plod1]

Yorkshire Devil, cheers for advice etc.
As soon as it goes limp again Im going to buy and fit the sensors myself. I have access to a mechanics workshop and ramps etc so it should be relatively straight forward.
Last time Merc did work on the car it was for a full engine drop to have the so called 'Fix' done for the power loss, replacement EGR and rerouting of wiring etc for sensor vibration.
I noticed recently as a result of this issue, that when they put the engine back in the car they failed to link the air filter holder with the connection to the side mounted air intake hose. Hence the car has been getting lots of dirt, water and dust and hot air in from the engine bay and wheel arch area instead of the cleaner air from the side vent. Ive changed the air filter and linked it up again, reset all the fault codes and surprisingly enough the car runs far better than it has since the original fix?
Im not sure what if any improvement clean air would make but seems to have done something.

[tolsen]

You should have called in witnesses and get them to issue an affidavit. Then go to Merc and claim compensation.

[plod1]

Well that wasn't a long wait!
It went limp again today, so turned off and restarted it. It ran ok so went to friends garage and borrowed his Autel pro708 scanner and read the codes.The dreaded p2359 came up again. Lost the paper with the live data values I noted on, but the downstream sensor was the same as last time I did it and the upstream one considerably different than last time.

It would be interesting to see if anyone has a diagnostic for them to run a live scan and read these values as a comparison to mine. Yorkshire Devil any chance you can do this on yours with your scanner?

Anyway Ive ordered the new sensors from Merc and will be fitting them next Thursday. Whilst Im at it with everything stripped back I am going to replace the alternator and air con belt and replace the fuel filter just for the hell of it. Is the fuel filter under the offside rear arch?

That will be a quick £200.00 down the pan.

[Yorkshire Devil]

Well that wasn't a long wait!
It went limp again today, so turned off and restarted it. It ran ok so went to friends garage and borrowed his Autel pro708 scanner and read the codes.The dreaded p2359 came up again. Lost the paper with the live data values I noted on, but the downstream sensor was the same as last time I did it and the upstream one considerably different than last time.

It would be interesting to see if anyone has a diagnostic for them to run a live scan and read these values as a comparison to mine. Yorkshire Devil any chance you can do this on yours with your scanner?

Anyway Ive ordered the new sensors from Merc and will be fitting them next Thursday. Whilst Im at it with everything stripped back I am going to replace the alternator and air con belt and replace the fuel filter just for the hell of it. Is the fuel filter under the offside rear arch?

That will be a quick £200.00 down the pan.

I will get you the figures this weekend.

[plod1]

Cheers Yorkshire Devil. Im just doing research on voltage readings of the two sensors how they should differ, the downstream remaining constant with the upstream fluctuating. I only tested mine whilst the engine was warm and idling, rather than at a constant 2,000rpm, which has been suggested on internet. So an idle comparison would be good for me, then I will check this week at a faster rpm and see what the results are.

A constant downstream volt reading indicates a healthy DPF whilst one that starts mirroring the upstream one indicates a faulty DPF, apparently. All very interesting but by knowing this you should be able to find out if theyre faulty or if there is a leak on one of the hoses, but dont qoute me on that as Ive absolutely know idea what it means! A faulty upstream sensor will be 'lazy' and not fluctuate quickly, so they say.

Comparing the readings with a healthy car should show if its the oxygen sensors DPF hoses or something else that I havent read about yet! Alternatively if someone has these values from the official workshop manual then that would be great.

Dnt you just love the internet for confusing everything.