S320 (W220) error code

[Richard46]

The engine fault light on the instrument cluster has come on, although the car runs smoothly with normal power. An OBD2 scan with a Mercedes scanner came up with the error "Particulate Trap Efficiency Below Threshold". My understanding is that this refers to a fuel particle trap for diesel engines, but my vehicle is fitted with the V6 petrol engine, and the code shouldn't be relevant. Any bright ideas?

A wonderful S Class vehicle to own that makes me look wealthier than I really am. Somewhere among the 70 fuses and five computers is an engine and gearbox, I believe.

[gazman]

Just a thought and I could be way wrong but could it be referring to the CAT?

[Guinevere]

A well old thread never resolved by the OP ?
I hate finding questions where the solution must/may have been found, but no one bothers letting other people know?!!!

Seems to me the last post was probably getting close to the money.

A CAT that is starting to block up will cause more back pressure- setting the code/ error.
Probably only first noticeable as a "condition of someting ain't right" whilst powering up on a steepish longish hill climb (my experience with a Holden VR Bommodore).

Solution, with a warmish engine, clear the error code, remove 02 (oxygen) sensors from exhaust, leave plugged in though for testing.
Start the vehicle and only run for a few seconds, don't want to start a fire now or suck those fumes into the cabin.
If you don't get the code coming back on startup, well guess what, you have reduced the back pressure.

So, CAT starting to block up or some other exhaust restriction... Banana in it?
I have heard of people ramming out the guts of the CAT with a steel bar... but driving with your car like that won't pass emission regulations and is thus illegal.

G

[CraigB]

yep, would love to know what happens with a lot of these. Do you know if there is any way to test flow of a cat? I have a 1990 'pre error codes' car with some pretty disappointing fuel mileage - working my way through things but I have wondered if I am just dealing with cat issues - has the pre cats too. Many years ago had an older car with a retrictive muffler and by replacing with a straight through resonator, not only got a big jump in power but also a big jump in fuel economy, so I guess that is in the back of my mind.