CLS Right hot film mass air flow sensor above limit

Tigerade

Active Member
Joined
Feb 21, 2016
Messages
63
Car
CLS 320 diesel
Right guys I'm after some help.

When I purchased my 2006/7 CLS cdi it needed a service, to cut a long story short it had one at my expense as the supplying Vauxhall dealer refused.

Anyway, once serviced a few faults were found and rectified by the dealer once they agreed they were current etc.

One of the faults was the Air flow sensor, Code:2645-001, Check component B2/7 (Right hot film mass air flow sensor ) value above limit.

The Air flow sensor was changed by the dealer 2 month ago but the exact same fault has returned, I'm wondering if A: The dealer never changed it or B: There's a bigger issue lurking and they thought I wouldn't find out until I had it serviced after the warranty period but I have, lol.

Thanks in advance,
Ade.
 
Last edited:

streethawk

MB Enthusiast
Joined
Jun 27, 2011
Messages
1,025
Location
leicester
Car
E320cdi sport
Right guys I'm after some help.

When I purchased my 2006/7 CLS cdi it needed a service, to cut a long story short it had one at my expense as the supplying Vauxhall dealer refused.

Anyway, once serviced a few faults were found and rectified by the dealer once they agreed they were current etc.

One of the faults was the Air flow sensor, Code:2645-001, Check component B2/7 (Right hot film mass air flow sensor ) value above limit.

The Air flow sensor was changed by the dealer 2 month ago but the exact same fault has returned, I'm wondering if A: The dealer never changed it or B: There's a bigger issue lurking and they thought I wouldn't find out until I had it serviced after the warranty period but I have, lol.

Thanks in advance,
Ade.

If it's a v6 which iam sure it is there are 2 and if it's a proper merc dealer they change whole y shape inlet which comes with both maf's as you can't buy them separately unless you look around. £300 for this part but it's very rare these fail on v6.
 
OP
OP
T

Tigerade

Active Member
Joined
Feb 21, 2016
Messages
63
Car
CLS 320 diesel
Sorry, yes its a 320 V6 Diesel.

The dealer informs me that he replaced the whole unit with a genuine MB item. The car is back in the dealers next week and believes it to be a problem elsewhere.

But what else can bring this code on?
 

streethawk

MB Enthusiast
Joined
Jun 27, 2011
Messages
1,025
Location
leicester
Car
E320cdi sport
Sorry, yes its a 320 V6 Diesel.

The dealer informs me that he replaced the whole unit with a genuine MB item. The car is back in the dealers next week and believes it to be a problem elsewhere.

But what else can bring this code on?

So the whole y piece with 2 maf's. ? If they replaced that thinking that was your problem and isn't then I'd tell them to put old unit back and give you you're money back and then find out the real problem.
 

streethawk

MB Enthusiast
Joined
Jun 27, 2011
Messages
1,025
Location
leicester
Car
E320cdi sport
Is it a merc dealer using star diagnostic. ?
 
OP
OP
T

Tigerade

Active Member
Joined
Feb 21, 2016
Messages
63
Car
CLS 320 diesel
The Star session was with one of the best Indies in my area, researched them, lol. I had the car put on "Star" as I wanted to make sure no faults were evident 2 months after being repaired.

The dealer from which I purchased the car also done there own diagnostics to confirm any errors, they have changed the whole "Y" section with both airflow sensors as it's one complete section and like I say, the error has reappeared.
 
Last edited:

streethawk

MB Enthusiast
Joined
Jun 27, 2011
Messages
1,025
Location
leicester
Car
E320cdi sport
The Star session was with one of the best Indies in my area, researched them, lol. I had the car put on "Star" as I wanted to make sure no faults were evident 2 months after being repaired.

The dealer from which I purchased the car also done there own diagnostics to confirm any errors, they have changed the whole "Y" section with both airflow sensors as it's one complete section and like I say, the error has reappeared.

I'd assume it needs live data checking whilst on star. Give olly a ring at prestige and he'll be glad to point you in the right direction as I always ring him if iam not sure. If you live near him go there honest I would but Portsmouth is a bit far.
 

gazz

Active Member
Joined
Mar 9, 2006
Messages
435
Has the car been remapped? I don't know why, but every v6 diesel I have seen that has been remapped throws this code, but runs perfectly. If the mil is off I wouldn't worry about it too much
 
OP
OP
T

Tigerade

Active Member
Joined
Feb 21, 2016
Messages
63
Car
CLS 320 diesel
I have no info as to the car being mapped or not.

When the dealers changed the airflow sensors it did seem to go better so I'd suspect something is throwing this code but as to what I don't know.

Like I say, the car goes well and I see a steady 46+mpg on my motorway commute at 60mph and at 79mph I see around 40mpg.
 

Auto-mobile

MB Enthusiast
Joined
Oct 1, 2011
Messages
1,600
Location
Birmingham
Car
2x c43 Amg clio 172 turbo 314bhp
Has the car been remapped? I don't know why, but every v6 diesel I have seen that has been remapped throws this code, but runs perfectly. If the mil is off I wouldn't worry about it too much

I have seen this on two occasions.
 

WG M-B

Auhorised Forum Sponsor
SUPPORTER
Joined
May 26, 2011
Messages
1,897
Location
N/W london
Car
C63 Wagon in black
If the car is driving fine but the code is getting thrown with no limp mode then I'd be sure that is a map issue
 
OP
OP
T

Tigerade

Active Member
Joined
Feb 21, 2016
Messages
63
Car
CLS 320 diesel
Ok, so next question is, how can I find if it's been mapped?

I have a raft of history but no invoices regarding any map.

Another thing is, when the dealer changed it and the fault cleared would this happen with a map or does it have to re-learn/teach the ecu and then the fault will reoccur.
 

Biltas

New Member
Joined
Jul 18, 2016
Messages
18
Car
Mercedes cls
same fault

I have same fault on my 2006 cls 320cdi, when i bougt my car 6 month ago check engine light comes on dashboard(car runs fine no limp mode mpg good) ,i plug star and snap-on diagnostic and have same fault code:2645-001, Check component B2/7 (Right hot film*mass air flow sensor*) first i try swap Right and Left maf sensors but this wont help , then leave car in garage they check maybe is air leaking but everything is fine!!! So now i want sold my car(need bigger car) but check engine light is on so i dont know what need to do (car runs fine without limp mode mpg good)
 

Biltas

New Member
Joined
Jul 18, 2016
Messages
18
Car
Mercedes cls
same fault

TIGERADE is check engine light is on dashboard on your car?
 
OP
OP
T

Tigerade

Active Member
Joined
Feb 21, 2016
Messages
63
Car
CLS 320 diesel
Hi Biltas,

There are no engine check lights on my car what so ever.
 

Biltas

New Member
Joined
Jul 18, 2016
Messages
18
Car
Mercedes cls
same fault

So i dont know what i need to do because car runs fine but engine check light is on! Any idea?
 

t-dawg1

Active Member
Joined
Jan 1, 2013
Messages
561
Location
Paisley
Car
Mercedes W211
gazz said:
Has the car been remapped? I don't know why, but every v6 diesel I have seen that has been remapped throws this code, but runs perfectly. If the mil is off I wouldn't worry about it too much

+1 mine has been remapped and has this code permanently. No mil or limp mode car drives perfectly
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom