KevinH2000

I have a 2005 C230 with 6MT. I bought the car with 112,000 miles on it in August 2017. The car currently has 183,000 miles on it and is running well. I replaced the radiator last week and the leak spewed coolant on the driver's side of engine bay. I didn't use the car for about two weeks while I gathered parts and found time for the work. Removing the radiator required me to take off the intake hose for the supercharger, but I believe I reattached it properly. I noticed that the O-rings on the hose were loose, but they slipped back on OK.

I occasionally have a CEL for code P0172 - System too rich. Previous searches indicated a possible problem with the O2 sensors which I replaced. The code went away for a while, but it has now come back. I also have two new codes - P0101 (Mass or Volume Air Flow A Circuit Range/Performance) and P2029 which my scanner doesn't identify.

The limited records I have on my car prior to purchase show that the previous owner replaced the Mass Air Flow sensor at 110,777 miles in March of 2017. The shop that did the work (Auto Service America in Northern Virginia) is not a Mercedes dealer and I don't know whether they used an OEM part.

Before I start throwing parts at the problem and investing time, I have the following questions:

1. Should I consider replacing the MAF?
2. Could the codes be related to the "$12-dollar hose" issue? $12 hose replacement.
3. Are there any other possible causes?
4. Is there a possible connection between the removal of the supercharger intake and the CEL's? Should I replace the O-rings on the supercharger intake?

Thanks in advance for assistance.

slammer111

Did you check the vacuum lines (4 in total) at the top of the engine? Sometimes they wiggle loose. They also crack over time.

KevinH2000

Thanks for the suggestion. I will check it out tonight.

KevinH2000

I checked the vacuum hoses, but I didn't see anything. I will need to devote more time and make a more thorough study this weekend.

Here's an update on my situation with the CEL: I drove the car to work and back today. On my morning commute, the CEL came on before I left my neighborhood. I read the codes at work and they were:
P200a-000
P202C-000
Neither of these codes were in my iCarsoft MBII Scanner's database.

I cleared the codes before I left work. The CEL did not illuminate during the majority of my drive home. I made one stop about 5 miles from home. When I started the drive home from my stop, the CEL illuminated in about two minutes. There was one code: P200a-000

The car drove well on the main part of my homebound commute. According to the display in the center of the gauge cluster, I drove 29 miles in 40 minutes. The average speed was 43 mph and my fuel consumption was 34.4 mph.

It seems like the car does well in continuous driving mode when I'm cruising between 65 and 70 mph. When I'm in stop and go mode or driving slowly, is when the CEL illuminates.

I found this generic information about code P200a. The author states that code P200A, means that the powertrain control module (PCM) has detected a problem with the intake manifold runner control (IMRC) system. The article also says, "The IMRC system is designed to regulate and reconfigure intake air as it enters the engine. At lower engine RPM levels, airflow is restricted in order to reduce exhaust emissions. At higher engine RPM levels, a swirling effect is created by the IMRC flaps. This helps to optimize fuel atomization and maximize engine performance."

This might explain why the CEL illuminates at low speeds and not high speeds. I will continue to search for Mercedes-specific (ideally M271-specific) information on this code.

I had one other problem while I was driving to work. The cluster-malfunction warning displayed in the center readout. That problem did not come back in the afternoon.

tkid

Hi, the air input to supercharger is via 110/1 at the rear of the engine, as shown below, pressurised-charge air is then sent via intercooler to the inlet manifold.
Working on the radiator, you would have had to remove pipes labeled 110/6. These carry charged air and the connection need to be sealed to prevent loss of high pressure!.
Any leaks there, can cause codes to appear..



M271 charge air transport

KevinH2000

Thanks for the reply.

You are correct that I removed that pipe. I've double-checked and the pipe is attached correctly. However, there are O-Rings at each end of the pipe. They were slightly loose. I think I will replace them to see whether that solves the problem.

KevinH2000

I was able to drive 30 miles to work and about 10 miles on my homeward trip without a CEL. However, the light did eventually illuminate. The codes today are:
P2029-000 - The information I found on a generic/non-Mercedes forum states: If your vehicle has stored a code P2029, it means that the powertrain control module (PCM) has detected a malfunction in the auxiliary or fuel fired heater system that has resulted in deactivation. This type of code is applicable to vehicles with fuel fired heater systems only.
P201C-000 - Self adaptation of mixture formation, The mixture is too rich in the part load range.
P2009-000 - a general OBD2 diagnostic trouble code indicating a fault within the intake manifold runner control circuit.

I didn't have time to put the car on ramps and remove the splash shield, but I was able to partially inspect the pipes labeled 110/6 in tkid's post. It appears to me that the top of the pipe on the driver's side could have worked itself out loose. (The end of the pipe is an aluminum collar that locks into the fitting with a spring clamp. It is difficult to access that pipe from above, so it is likely to be Friday night before I can remove the splash shield and determine whether that could be the source of the CEL. I do remember having some difficulty reinstalling that pipe and it is definitely worth my time to check it thoroughly before chasing after other potential problems. Here's a photo of the pipe connection. You can see it below the top radiator hose:


I contacted the Mercedes dealership and ordered two new O-rings for that pipe. It may be wishful thinking on my part, but I believe I can hear an air leak coming from that side of the engine when I accelerate.

Thanks again to tkid for pointing me in this direction.

slammer111

Did you also inspect the other hoses such as the EGR one (labeled b in the diagram) for cracks?

KevinH2000

I picked up the O-rings from the Mercedes dealership last night. I won't have an opportunity to install them on the car until I finish work today. I will check the EGR hose when I install the O-Rings on the supercharger pipes.

I will provide an update after I finish, but I expect that I will need to drive the car a few times to determine whether the air leaks in the supercharger air system were the cause of the problem.

As I said earlier, I was experiencing occasional CEL problems before I replaced the radiator. In retrospect, I think I may have had minor leaks in the air system that were exacerbated by removing and reinstalling the pipes. If anyone else faces this situation, I recommend that they plan to replace the O-Rings when they reinstall the Supercharger pipes.

KevinH2000

On Friday evening I installed new O-rings on the supercharger pipe connections that I unfastened during the radiator replacement. I also inspected the EGR pipe and it looked OK. Since then, I have driven the car about 50 miles on a variety of errands. The CEL has stayed off.

I don't think I had correctly reattached the top of the supercharger pipe (110/06 on the right side of tkid's diagram) where it attaches to 50/1. It is difficult to apply force to this pipe while attaching it. I had to push on it from below the car. I used a screwdriver and pressed upward on the metal collar where I couldn't put my hand on it. The O-ring may have rolled out of position and interfered with the attachment.

The next test will be my commute on Monday.

Thanks to everyone who provided suggestions.