ScootScoot
New Member
First post - hello to all.
My car is a 2015 E250 CDI estate, OM651 engine. It's covered 118,000 faultless miles (50k with me) and up until recently my daily commute gives me 54mpg (+/- 2mpg), which is stunning for a big car. No faults, ever. Religiously changed the oil and filter every 8k, changed the transmission fluid last July.
About 3 weeks ago, I noticed that the radiator fan was reaching a high speed after approx 30 seconds after ignition. Even from cold (at 2C or 3C outside temp), to be honest I didn't immediately notice the drop in economy. The indicated engine temp reaching it's standard 90C after about 15 mins of driving. I'm also pretty sure that one day it didn't spin the fan up at all during my 40 mile commute home. If I turn the engine off back to position 2, the fan stops. So it's not the 'constantly on' problem.
I've read the existing threads about 'noisy fan' / 'radiator fan speed' and the AC Pressure Sensor fix. I'm hesitant to go there purely because of the drop in economy and wanted to ask opinion if you think that the overcooling from the fan is dropping the economy by not letting the engine reach it's economical temperature. Or that the fault is another sensor more related to fuelling, which in turn is signalling the ECU to a fail condition.
What I have noticed is that my MPG reading from cold is now starting at 14.1 MPG. I'm pretty anal when it comes to MPG, almost certain it never used to do this, leading me to think it's going into some limp mode condition although the engine power doesn't seem 'down'.
The relatively basic scanner I've got is a Launch CRP129 with up to date files, but I would have thought good enough to catch a code. There are no fault codes. The only 'live feed' mention of any error is in the EGR section. "Y85 EGR cooler bypass switchover valve Fault. 53336/6058" - this value changes to 'OFF' during driving. Other people have mentioned this but not in relation to a fan speed issue. I don't think this is anything.
So far, I've changed the coolant temperature sensor, original part from Merc. No change.
I took the car to my local diagnostic centre, in fact they passed the MOT the previous week when the car had the fault and we mentioned booking it in. The diagnosis was a faulty radiator fan controller, I've got this in writing on the bill. Purchased a Ridex fan shroud from Autodoc and fitted this myself, no change - just the same.
On the verge of calling the guy back and giving him a 2nd chance to diagnose, but hesitant due to his previous mis-diagnosis.
Thoughts? Apart from "god, that's a long post" ;-)
My car is a 2015 E250 CDI estate, OM651 engine. It's covered 118,000 faultless miles (50k with me) and up until recently my daily commute gives me 54mpg (+/- 2mpg), which is stunning for a big car. No faults, ever. Religiously changed the oil and filter every 8k, changed the transmission fluid last July.
About 3 weeks ago, I noticed that the radiator fan was reaching a high speed after approx 30 seconds after ignition. Even from cold (at 2C or 3C outside temp), to be honest I didn't immediately notice the drop in economy. The indicated engine temp reaching it's standard 90C after about 15 mins of driving. I'm also pretty sure that one day it didn't spin the fan up at all during my 40 mile commute home. If I turn the engine off back to position 2, the fan stops. So it's not the 'constantly on' problem.
I've read the existing threads about 'noisy fan' / 'radiator fan speed' and the AC Pressure Sensor fix. I'm hesitant to go there purely because of the drop in economy and wanted to ask opinion if you think that the overcooling from the fan is dropping the economy by not letting the engine reach it's economical temperature. Or that the fault is another sensor more related to fuelling, which in turn is signalling the ECU to a fail condition.
What I have noticed is that my MPG reading from cold is now starting at 14.1 MPG. I'm pretty anal when it comes to MPG, almost certain it never used to do this, leading me to think it's going into some limp mode condition although the engine power doesn't seem 'down'.
The relatively basic scanner I've got is a Launch CRP129 with up to date files, but I would have thought good enough to catch a code. There are no fault codes. The only 'live feed' mention of any error is in the EGR section. "Y85 EGR cooler bypass switchover valve Fault. 53336/6058" - this value changes to 'OFF' during driving. Other people have mentioned this but not in relation to a fan speed issue. I don't think this is anything.
So far, I've changed the coolant temperature sensor, original part from Merc. No change.
I took the car to my local diagnostic centre, in fact they passed the MOT the previous week when the car had the fault and we mentioned booking it in. The diagnosis was a faulty radiator fan controller, I've got this in writing on the bill. Purchased a Ridex fan shroud from Autodoc and fitted this myself, no change - just the same.
On the verge of calling the guy back and giving him a 2nd chance to diagnose, but hesitant due to his previous mis-diagnosis.
Thoughts? Apart from "god, that's a long post" ;-)