S212 E350 CDI - CEL on - Loss of power

[bumblbee]

Hi everyone

So, it's been a while since I was on here. Last time I was with a 2001 S210 estate, so firstly thanks for all the previous help and advice!

I know I'll get a telling off, but bought another estate just yesterday; an S212 E350 CDI, 7 seater, memory seats, 2 owners. Done 120k miles (114k in first 6 years). No service history came with the car, but I tracked down the official Mercedes history and that was taken care of up to 35k, must have been local garage after that.

Bought without testing it. I know. But it ticked all the boxes for our family and growing Ridegback who needs good boot space. Really pleased with overall condition and drive quality - bodywork looks great but the alloys could do with a refurb (only other problem is a disc sounds stuck in the head unit). It also has a 6mth warranty. I have booked it in with a top Merc indie specialist for Monday diagnostic and possible fix if parts are in. I don't want the dealer to fix it as they're quite far away and nowhere near as good as the specialist near me (they don't specialise in Mercs).

It would be good to know if anyone has come across this problem before and if it is an expensive fix?

On to the issues:

YESTERDAY:
- Car was delivered by an independent company who drove it 3.5hrs here without issue or fault. I trust them as I employed them, dealer had no relation to them. Said it drove great.
- I then go for a test drive and everything is fine. I then take it for a 1hr journey and around 20mins in I notice it won't kick down and accelerate hard when I need it to. Won't rev past 1,500-2,000RPM.
- OBDII scan showed P0101 Mass or Volume Air Flow Sensor A Circuit Range/Performance
- Arrived at destination. Engine off for 10mins. Reset CEL. Drove for 5mins acceleration good. Then started the journey back home and acceleration disappeared as before, but no CEL.

TODAY:
-Started car this morning for school run. Acceleration initially good, then CEL and same as before. No acceleration past 1,500-2,000RPM.
- Returned home and scan came up with:
P0101 Mass or Volume Air Flow Sensor A Circuit Range/Performance
and P0234 Turbocharger/Supercharger A Overboost Condition.
- Live data: IAT 37; MAF 0; TP 91; FRP 29980kpA; FLI 31; CATemp12 144.8 deg C; VPWR 14.720; TD_R 94.9%; AAT 13 deg C; APP_D 5.1%; APP_E 5.5%; TAC_PCT 96.5%; MIL time 21m.

Appreciate has a warranty (though we'll see whether that's worth anything soon enough!) and is booked in for a check, but just hoping for some advice and guidance on possible causes/cost. Once it has been looked at I will of course post back with the findings too so maybe it can hep a few people.

Thanks in advance for your help. Really love the car and I'm hoping it's not a lemon!

 

[bumblbee]

So, an update:

Jumped in car just now to go for a 20min run. Check engine light still on.

Absolutely no problems with accelerating. Tried with AC and without. All good.

Returned home. Same fault codes shown as Pending. Cleared check engine light and fault codes.

Turned car back on. Same problem returned, but no check engine light. Power restricted to 1,500-2,000RPM. Can't rev higher than 3,000RPM in park.

Look forward to hearing some advice on this one

 

[Larkone]

I would be investigating the turbo actuator (gears likely gummed up with carbon) and if the turbo vanes are moving freely. The actuator doesn't always throw a code, mine didn't when it started to play up. As it is covered by the 6 month guarantee from the dealer let them sort it. Refurbed actuator is about £100 plus labour to fit (<30mins)

 

[Blobcat]

So, an update:

Jumped in car just now to go for a 20min run. Check engine light still on.

Absolutely no problems with accelerating. Tried with AC and without. All good.

Returned home. Same fault codes shown as Pending. Cleared check engine light and fault codes.

Turned car back on. Same problem returned, but no check engine light. Power restricted to 1,500-2,000RPM. Can't rev higher than 3,000RPM in park.

Look forward to hearing some advice on this one

Can't rev higher than 3,000 in park isn't a fault - it's designed that way to protect the engine

 

[bumblbee]

I would be investigating the turbo actuator (gears likely gummed up with carbon) and if the turbo vanes are moving freely. The actuator doesn't always throw a code, mine didn't when it started to play up. As it is covered by the 6 month guarantee from the dealer let them sort it. Refurbed actuator is about £100 plus labour to fit (<30mins)

Thanks for this. Good idea to check that.

I'm a long way from the dealer but they have offered to pay if it's not too expensive. Or they'll just take it back if it is. Because it's a distance sale, the pressure is on them to sort it out quickly. The car is great otherwise.

 

[bumblbee]

Can't rev higher than 3,000 in park isn't a fault - it's designed that way to protect the engine

Great to hear. I did wonder that. The thing I can't understand is surely I shouldn't be able to accelerate hard with the engine light on? It doesn't make sense to me that when the code is reset the acceleration is restricted but no CEL, whereas before when the light was on when I last went out it allowed me to accelerate as I pleased!

 

[Mr Greedy]

Whatever this is, is doesn't sound like a warranty issue. It sounds 100% like a pre-existing fault. I would expect any warranty company to refuse to pay out on this because pre-existing faults are not covered by warranties.

As a pre-existing fault, the car trader needs to fix it, or I guess take the car back (so they can sell it to someone else who hopefully doesn't know their consumer rights law, and just puts their hand in their pocket to fix it).

 

[bumblbee]

One thing I’ve noticed is the engine temp display gauge doesn’t go above 70 degrees either.

 

[Wighty]

One thing I’ve noticed is the engine temp display gauge doesn’t go above 70 degrees either.

That’s just an additional thermostat failure

 

[supernoodle]

Overboost Condition.
- Live data: IAT 37; MAF 0; TP 91; FRP 29980kpA; FLI 31; CATemp12 144.8 deg C; VPWR 14.720; TD_R 94.9%; AAT 13 deg C; APP_D 5.1%; APP_E 5.5%; TAC_PCT 96.5%; MIL time 21m.

I don't know if you really meant live data or freeze frame, either way MAF of 0 isn't good as this was clearly engine running with FRP of 29980kpA.

 

[bumblbee]

I don't know if you really meant live data or freeze frame, either way MAF of 0 isn't good as this was clearly engine running with FRP of 29980kpA.

Sorry, I meant it was a photo idling at 5-600rpm.

The MAF did increase with the throttle, but from your comment it sounds like it should be reading even at idle.

 

[bumblbee]

Drove for an hour into Norwich this evening. Halfway through lost the acceleration again. No lights on dash though.

Watch my son train for two hours. Then back in the car. Check engine on this time, but acceleration all fine.

I’ll be interested to see what the problem is on Monday.

 

[bumblbee]

I don't know if you really meant live data or freeze frame, either way MAF of 0 isn't good as this was clearly engine running with FRP of 29980kpA.

Just saw your post back in February on how to calculate the expected MAF output at idle. Very impressive!

 

[bumblbee]

UPDATE: FIXED!!!!!

Thought I'd hopefully help someone else who comes across a similar problem with their W212 check engine light and can't get to the bottom of it.

So, took the car to Alex Crow in Stowmarket for review (not too bad as we're in North Norfolk):
He completed the A service and check. Smoke test. No clear leaks. Signs of leak at turbo. 'O' rings replaced. Check Engine Light off on check. Back on when I drove off (typical!!).

I was travelling near Harrow over the next few days so begged Terry at Wayne Gates (who used to service my old estate) to take a look and see what he thinks. He could not pinpoint the problem, but suggested sorting the DPF - chemically cleaned DPF, replaced DPF pressure sensor, exhaust back pressure sensor, regen and STAR test. Air mass meter plausibility codes still present. Check Engine Light off. 25 mins later it came back on. Terry suggested the last thing he thought it could be, without scanning (as I was quite far away by now) is the clean air line that has the air mass sensors either side. A6420901642 for my vehicle.

Continued to drive the car, with intermittent loss of acceleration. Booked in another session with Alex Crow who analysed the clean air line air sensors, running specific tests and found one failed; he swapped them over and the fault followed - definitely the sensor! Interestingly, you can buy the individual sensors on my model but they are still prohibitively expensive for what they are.

Managed to find one on the Bay for £150 (Mercedes wanted £900), from a CLK with the same part number and only done 70k on the clock. Alex kindly fitted it for me and the problem has not been back since.

Really happy it's all fixed, and credit to both Terry and Alex for getting us to the true cause of the problem without too much fuss.

The car has been running great, apart from the 4 different tyres the previous owner put on in the past. So I've rewarded her with 4 new Michelin Pilot Sport 5 tyres. Alloys need a refurb, but the car feels a lot better on the new boots.