14CF00 The positive control deviation of exhaust gas recirculation control is too high - ongoing saga of my car which is breaking my will again.

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gmacalex

Member
Joined
May 24, 2023
Messages
37
Location
Glasgow
Car
Mercedes E350 Cdi Coupe 2008/9
Since last on the forum my car has been a continuous nightmare, its been back to the garage to have swirl flaps done, which was painfully expensive, and the car did perform ok afterwards, but then the juddering, almost missing a beat returned, surging at low revs, slow pick up. So egr was replaced, and car again worked ok not brilliant for a few days. On my reader the continuous code that pops up, occasionally puts the car in limp and warning light is 14CF00. I have searched for broken wires visually and by pulling gently, I am not a spark so it's trial and error. I have tried another egr just in case, but same result. Today I removed the cover from the turbo actuator, it looked clean enough, it didn't seem to be worn, I gave it a quick clean with contact cleaner and a touch of high temp grease on the cogs. Test drove the car got quite excited that it did feel better but on my return the surging and bucking returned, the only code showing again 14CF00. Do you think it's worth trying a new actuator? could it cause this code, is this code even likely to be causing the the very annoying surging and bucking at low revs? Really at a loss about what to do, I have tried everything that I think I can do, I can't afford the garage due to the big cost of swirl flap replacement, the actuator seems to be my last opportunity to fix.

I have attached a couple of photos of the actuator and a blue plug which didn't seem to have a home, bit concerning but maybe its for something my car does not have.
As always any advice appreciated. Thank you
 

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I’d be very tempted to try an air mass meter (batwing). There’s a test in Star that modulates the egr valve and you have to see the air mass response within a set range. If it’s not in the range you get this fault code. Don’t be tempted with cheap ebay batwings - I’ve never seen a good one. A swap with one from a known good car is a reliable test.
 
That sounds like a plan I cleaned the maf sensors when looking at the actuator I will try and source one. Thank you for responding.
 
@Jobsworth
Any view on an unused connector?
Seems unusual to me.
Could that be from under the batwing? Two connectors?
Or swirl flap motor?

@gmacalex
Have you got a better photo of the unused connector location please?
 
Hi, Thank you for responding, sorry don't really have better images, the wire/plug was tucked beneath the wiring harness in photo (shiny black) I did have to dig it out, I was hoping this was a magic bullet fix, but I searched all around the are and could not find anything where it could be plugged and just assumed it was for something my car did not have, the batwing has two Maf plugs and the orange pipe plug, no other sockets, the plug was under the batwing.

Thanks Gordom
 

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I’d be very tempted to try an air mass meter (batwing). There’s a test in Star that modulates the egr valve and you have to see the air mass response within a set range. If it’s not in the range you get this fault code. Don’t be tempted with cheap ebay batwings - I’ve never seen a good one. A swap with one from a known good car is a reliable test.
I managed to get a loan of the batwing from a similar aged car, unfortunately after initially being much better it returned to surging and bucking. Worth a try and it has ruled something out which is good . Thank you
 
I don't know id this is relevant or perhaps and indicator, when replacing the batwing yesterday, a could hear in the engine a faint but regular beeping noise, not loud and could not be heard inside the car, sounded like an alarm beep beep beep etc couldn't locate exactly where it was coming from, maybe something is unplugged?
 
I have been there with your fault a few times.

1. Are you fitting genuine EGR valves? If not, you certainly need to. The cheap ones sold are pointless as they don't last/work. They are currently back order and have been for a while so we map them out now.
2. The usual reason for this code is a blocked EGR pipe or throttle flap issue. There are some metal EGR pipes on the front of the engine that clog with soot and that can cause this kind of limp mode/fault code. Take off the throttle flap and pipes and give them a good clean. re-set all of the adaption data (HFM drift compensation in Xentry diag actuations menu)

I hope this helps.
 
I have been there with your fault a few times.

1. Are you fitting genuine EGR valves? If not, you certainly need to. The cheap ones sold are pointless as they don't last/work. They are currently back order and have been for a while so we map them out now.
2. The usual reason for this code is a blocked EGR pipe or throttle flap issue. There are some metal EGR pipes on the front of the engine that clog with soot and that can cause this kind of limp mode/fault code. Take off the throttle flap and pipes and give them a good clean. re-set all of the adaption data (HFM drift compensation in Xentry diag actuations menu)

I hope this helps.
Really appreciate the information and guidance, the EGR is a refurb Wahler part, the second part of your reply is above my ability, no idea where the egr pipe in the front is or where the throttle flap is, its dark now here but I will have a look tomorrow and see if I can make sense of the pipes and if it is something I could try. Many Thanks
 
Hi, so I decided to go back to the start, I cleaned and put on the original EGR, managed to get it installed without the coolant leak of previous attempts. I couldn't see the pipe suggested by BlackC55 so I cleared the 14CF00 code and went for a drive, car seem not to bad, no warning light, definitely improved on its previous state. I pulled in check my code reader and no codes, drove for about half an hour car started to return to previous form, when driving it feels like I have dabbed the breaks, before there was ABS, its very annoying and not really that drivable, car then seemed ok for a while but did then jolt several times before I got home. Again however when code reading no 14CF00 code, or warning light so perhaps the ERG was rubbish as suggested, I can't see the code need on the actuator to order one, I guess you have to remove to see it, which is a pain. Anyway that's my update, little tiny bit further forward.Cheers
 

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