P029921 is “ The boost pressure of turbocharger 1 is too low” Mercedes-Benz C180 Se 2013
Took the car to one of the garages and they could not find anything visible, but they said apparently this is a very common problem with mercedes and more than often even changing the turbo doesn't solve the problem and the cant really be sure what part to change.
I did a lot of research online and I got varies things such as wastegate actuator or most probably the map sensor or blow-off valve (P/N 000-153-11-59). I cant really find the blow off valve i am not sure if my car even has it.
A little history 2 weeks after servicing my car and changing the spark plugs and flushing the coolant I start getting this code.
The car goes into limbo and become very sluggish and doesn't speed properly. engine light doesnt come up.
At the time the engine was cold and after turning the car on and off the problem resolve itself.
| Mercedes-Benz | |
| C180 Se Blueefficiency |
year 2013 and 56k miles on the car
They reset the the fault yesterday and I have been driving it around and went back after a day and the code doesn't come up anymore, but I am sure the problem cant just go by itself, but its strange that the code hasn't come up again,right?
Any ideas suggestions?
Thank you
First off, your turbo definitely has a turbo bypass valve (what you call "blow-off valve"). It is an electronically controlled valve attached directly on the compressor side of the turbo. Most of the time boost pressures being low are either caused by: air leaks on the charged-air side (compressor side of turbo, the intercooler, and piping to the throttle body), or a bad turbo bypass valve. You really want to make sure all your hose clamps/clips are tight...it's a pressurized system so you don't want any boost to escape from loose clamps. Be sure to inspect the wiring/connections for the bypass valve.
The wastegate (controls the amount of exhaust gas used to spin the turbine) is found on the exhaust side of the turbo, and usually they rarely go bad. Now I believe your wastegate is pneumatically controlled, so be sure to check the vacuum lines associated with it, otherwise it may not work properly. Best way to test this is to start your car, and have someone rev the car while you are looking at it. You should see the wastegate arm open and close as the person revs the car. If not, then that could be your problem.
As for the MAP sensor(s), make sure it's working properly. That is the only way the engine sees how much boost the turbo is making, and I believe there are two on your engine (one on the charge piping and one on the intake manifold itself). Clean them if you need to and inspect the wiring/connections.
Did you do the spark plugs yourself? If yes, did you torque them down correctly? Improperly torqued spark plugs will cause compression leaks.
@razmigb
Wow thank you so much for the detailed comment I did not expect to get such amazing response I will check everything you said.
It was my friend who did the spark plugs but I guess I could take it to garage to take them out and put new ones if that is causing the problem as the first step.
Well for an even easier first step, just take a look at all your turbo plumbing and make sure you don't feel/hear any leaks. How often does the issue come up?
I specifically addressed spark plugs last because that would be the least likely problem...it wouldn't cause significant pressure loss even if they were the case. There is a significant boost loss for the ECU to set a code like that and put the car in limp mode.
@razmigb
It only happened twice and after resetting the computer it hasn't happened yet.
Pipe work are all seem to be ok and no unusual noise, we did rev the car a little to see if anything moves around the turbo and did not notice anything
@shaya
Ok. But make sure you check the wastegate actuator as well to see if it's working. When you rev the engine, the actuator arm should "retract" to engage the turbo. When the car settles down the arm should "extend" to disengage the turbo. Maybe it was a computer glitch and the reset helped fix it...
Good morning, I have the same problem, did you find a solution?
@shaya Did you manage to find a resolution to this? I have a 2013 C180 too and I’m having the exact same problems, trying to avoid changing the turbo if there is a cheaper option which will cure it! Thanks 🙂
@abbie-thompsonlive-co-uk Good morning, I have the same problem, did you find a solution?
@abbie-thompsonlive-co-uk This topic is over 4 years old so you are very unlikely to get an answer. It would be better if you started your own, new topic giving a clear and concise description of the vehicle, the problem, and any diagnostic steps taken so far.
@chucktobias the comment is by @kevinortiz12 not abbie
@imperator Sorry, lost track! Your mentioning @kevinortiz12 should direct his attention here.
Hi,
I’ve got similar issue as yours and not sure what to do for best. I’ve replaced my MAF sensor and a week later, the speed was intermittent, well back to its old self, limp mode! Got another diagnostic test done today and it’s coming up with turbocharger 1 boost pressure too low. Is it worth repairing or is this just a money pit?
faults:
- The turbocharger 1 boost pressure is
too low.
- A leakage is identified in the inlet air
system. The signal comparison is
faulty.
- Output 2 for the low pressure
turbocharger is faulty. The actuator
does not close.
- The pump current connection of
oxygen sensor 1 (cylinder bank 1) has
an open circuit or other electrical
faults. An open circuit exists.
Thanks in advance for all your help.
I have the same problem as you guys.
I drive an c180 cgi coupe from 2013.The fault code says boost pressure under minimum (029921). If the problem occurs, the car has no boost and drives hardly 70 km/h.
You can hear that there is no boost because the blowoff valve makes no noise. The problem occurs only when it is over 20 °C outside and it sometimes resolves itself by restarting the car.
I already checkt the turbo, its fine.
I already changed :
blowoff valve, bypass valve, all relevant sensors like Map or Temperatur sensors
The wastegate also works fine and there is no leak in the pressure system (that I can see)
I hope someone can help me with that or has any suggestions.
thanks in advance
hey C180cgi, can you tell me if you have issues when you are filling up with gas ? if the pump keep disarming when you are pulling the trigger ? I'm guessing the canister (active coal filter) which is attached to the fuel tank is causing the issue. Had exactly the same scenario you posted. Have you fixed the issue already ? Since you posted that a month and half ago... thx !
I don’t have a problem when filling up with gas. It turned out to be the AGR (exhaust gas recirculation/Abgasrückführung ). The valve that opens it is stuck open due to carbonization so the boost could get out of there. I didn’t want to change the part so I just closed the pressure system so the AGR can’t work anymore. Haven’t had a problem since and the fuel consumption got lower
You can find out it that’s the problem if you just pull the pressure-tube off and put a screw in so that it is closed up. The AGR can’t work then.
Hi
Did you find a resolution to this.
I am in a similar situation
Gla 200 petrol 2018. 2 weeks out of large service have got to faults P246300 and P29921, and the engine light is on. Wife was driving it on motor way and wouldn't accelerate properly, possibly went into limpmode.
Any suggestions? 🙁
