Engine Idle holds at 1500RPM & then comes down to normal with the Aircon switched on only.

Once got error code P0600 but cleared it & now there's no faults showing but the problem persists!!

any ideas ? any info ??

I would have the aircon checked for leaks / gas level

Thanks for the input bluecar1

Further experiments conducted & I gather it's a constant problem ! Aircon or no Aircon ... problem persists !

is the ELM327 OBD2 reader reliable, any one ?

so aircon was a red herring

 

rise of rpm to 1200-1500 at idle is normal if an active regen of the DPF is taking place

 

give it a long run at 2000-2500 rpm in 4th or 5th on a good road for 10-15 minutes minimum

 

if the dpf is the issue and that doesn't clear it, it could be a faulty sensor on the DPF, not exactly unknown

bluecar1 , Aircon was the red herring & a waste of time..

actually the idle doesn't come down while driving I.e. while de clutching to up or down shift the engine rpm holds at around 1500 & then gradually comes down !

also while driving if I leave the gas pedal the car still carries on moving instead of slowing down, like the engine is receiving fuel ...

Carista app with a wifi ELM327 dongle doesn't show any faults, but I found on close inspection of the engine bay, the ECM had popped out of its cradle & was resting on the air mass sensor on the filter / intake pipe.

A friend gave me an idea of checking the butterfly valve but don't know if diesels have one ?

do you have any floor mats ? had a few cases on here of floor mats fouling the throttle pedal and giving the symptoms

 

sounds like a sticky throttle or throttle sensor is faulty

 

if you have the idle speed high, if you stick your toe under the throttle pedal and lift it does it then return to normal?

nope, not floor mats !

This happens more when the car is heated up dues to being parked in the sun. it's more pronounced once the car is got it's fair share of the Suns heat.

petrol of diesel?

 

which engine size?

would not have thought it had butterfly valve, if I am thinking of the old valve or flaps carb engines used to have. (I might be wrong though). The Fabia uses a "Drive by wire" Throttle, not an old cable system so would be fuelled by the ecu

@mrgf

So Ecu could be getting wrong readings ?

VAG COM not showing any readings out of sync

However, today I added some injector cleaner & the engine has settled into a smooth idle, it feels much more responsive.

The engine revs still sticking. But it took a longer time for the engine revs to stick.

Leads me in the direction of a mechanical issue.

Maf Maf Maf .....

MAF failure usually results in a flashing glow plug light and engine unwilling to go over 3000 rpm

 

not heard of it causing a high idle speed

There wasn't any dash warnings, the MAF was functional but not properly.

Appears the ECM cradle was flimsy & the ECM had popped out of its cradle & was resting on the MAF sensor socket. A wire or two was damaged with the friction!!

MAF changed, wire insulated with a shrink sleeve. All errors cleared (there were none) & tested for the last 2 days. Touchwood, all is good !

glad you got a result