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Fixing an air leak in the P202B/P2007 system using a DIY method.

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Following the replacement of the rocker cover gaskets on my W211 E55, the car operated well for a week. However, after extended periods of driving, the vehicle began to experience jolting during deceleration, difficult downshifts, the illumination of the check engine light, and an uneven idle.
While driving on the motorway was OK, the issues became apparent while encountering frequent stops and starts in traffic.
This closely resembles a frequent occurrence known as a "hiccup" in the 55 AMG model, which is often reported after switching to a bigger throttle body.
In this scenario, the symptoms exhibit similarities but might arise from several origins, with the common factor being discrepancies between estimated and real air intake charges.
The system is MAP-based on the 55's, meaning it does not use an airflow metre. Instead, it relies on a Manifold pressure sensor. The ECU matches this sensor's readings with the throttle position to determine the level of vacuum or boost and hence estimate the engine load. From an electronics perspective, engine "load" refers to the quantity of air that the engine is taking in. For instance, when the throttle is fully open, the engine may be drawing in a large amount of air with low vacuum or even experiencing positive pressure or boost. Conversely, when the throttle is closed, the engine creates a high vacuum as it pulls against the closed throttle, resulting in a "throttled" effect.

The MAP sensor monitors the variation in air volume inside the engine, allowing for Wide Open Throttle to be achieved both at idle and at the redline, but with varying levels of air intake.

Now, let's return to the matters at hand.

The following are the categories of codes that may indicate an air leak or hiccup:


Disregard P2027, which is clearly identified as the IC auxiliary pump. I will monitor it closely to see if it reoccurs. In any case, I have already ordered a Bosch 010 pump.

The probable codes that may be seen are P2007 - 008 B28, indicating an improbable signal from the pressure sensor.
The load limit is now active with the code P1999, indicating a duration of 20 days and 4 hours.
P202B - Idle speed control implausible - Electrical malfunction caused by a low-resistance connection that allows a current to flow via an unintended path, bypassing the normal circuit.
P20A2 - Idle speed control is not believable. - Inspect the system for any unmeasured air

The B28 Pressure sensor, also known as the MAP sensor, is located on the left side of the rear of the supercharger when facing the engine from the front of the automobile. Despite using an endoscope to explore, I was unable to get even a brief view of it. Fortunately, these occurrences are few, so there is no need for you to consider making any alterations.
The code P202B perplexed me for some time. The term "short circuit" is an inadequate or incorrect description since there is no idle speed controller present. Instead, the idle is controlled by the throttle. Disregard the presence of a short or open circuit in an M113K. Instead, interpret it as a deficiency in idle control.
The significance of P20D4 has been previously discussed, and I am certain that it may be interpreted literally as a power limitation in the form of a limp mode, often achieved by not engaging the 'charger clutch.

Earlier, I received a gearbox code indicating a severe downshift while the engine was experiencing rough idling and the vehicle was bouncing on the road, as the automatic gearbox system struggled to maintain stability. If you encounter a situation of similar kind, refrain from panicking immediately.

Upon studying the analogous "hiccup" problem, it becomes evident that it exhibits similar patterns. Specifically, the driving experience is seamless when the engine is cold and there are no issues on the highways. However, after around thirty minutes of driving, releasing the throttle might result in misfires, unstable idling, and ultimately trigger the check engine light.

In my situation, the issue began 4-5 days after replacing the breather and rocker covers. This timing was too significant to attribute it to other potential problems like a faulty MAP sensor or throttle. There have been reports of them rectifying problems with other individuals' vehicles, but there is strong suspicion of an airleak.

The root reason in my situation was the evap/purge valve pipe, which is likely to be a common problem after a rocker cover replacement.


The purge line, which is used to release fuel tank vapour pressure, is secured by a bracket attached to the rearmost bolt of the rocker cover. Frequently disconnecting the pipe may be achieved by removing this bolt and pulling the line out of the way.




The solution is rather simple; it only has to be returned to its original location. To get access, it is necessary to remove the plenum of the "Surge tank". This may be done by unscrewing the approximately seven torx screws located on the top. Additionally, there is one screw in the back portion of the "round" pipe.

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Utilise an air duster to remove debris from the space between the plenum and the charger. I removed my to discover Southend Seafront concealed.


In order to complete the task, it was necessary to promptly use Henry, the vacuum cleaner, to suck up any debris by attaching a flat upholstery tool to the intake ports. Finally, a transparent silicone hose was taped to the end of the vacuum to thoroughly clean the ports by applying carb cleaner and extracting any remaining residue. Due to the adhesive nature of grit, vacuuming alone is insufficient to completely remove it, especially when it is mixed with oil residues.
Ebay offers a wide range of endoscopes that may be connected to your smartphone to examine the condition of objects.
While it may be difficult to completely prevent dirt from accumulating in that area in reality, you may mitigate this issue by first blowing out as much dirt as possible and ensuring that a hoover is readily available to facilitate the cleaning process.

I cannot provide an assessment of the safety of using a vacuum to suction carb cleaning and its vapours. However, if you want to go with this task, it is imperative that your assistance securely holds the vacuum and maintains a considerable distance from you. Additionally, it may be advisable to use ear protection. In the event of an explosion, helpers often possess a safety mechanism that prompts them to quickly retreat and extinguish themselves with water, allowing you to continue with the engine-related tasks.


The pipe has been successfully repositioned.


In summary, if you have recently replaced your rocker covers and are experiencing issues such as poor idle, deceleration misfires and check engine lights, it is advisable to inspect the purge valve pipe. This pipe is often dislodged from its seat when moving the purge line bracket away from the rocker cover. It is important to note that the pipe is difficult to detect without removing the plenum, and repositioning it can be challenging without a clear view of the task.

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Hello, I have recently changed all the plugs/leads and also replaced the rocker cover gaskets. About a week later, the car's performance significantly deteriorated, with poor deceleration and idling, accompanied by the occurrence of similar error codes. I was feeling quite frustrated till I stumbled over this post while doing a Google search. I registered to express my gratitude for providing this information.
Thank you for preventing me from incurring the expense of replacing the throttle body, since that was going to be my next step. Therefore, if you ever find yourself in New Zealand, I am indebted to you and will gladly buy you a drink.

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I believe this is the underlying reason for the irregular engine speed and performance.

I inadvertently dislodged this pipe and am uncertain about its proper installation. Therefore, I want to readjust it over the next weekend. I appreciate the provided information.

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Yesterday, I replaced the valve cover gaskets. After doing so, I began experiencing the P202B error and the P2007-000 problem. I removed the valve cover bolt for that specific line, and it is evident that I successfully loosened it yesterday. I managed to resolve the issue quickly over my lunch break.

I am indebted to you and will provide you with a beverage of your choice. If you choose, direct message me your email address and I will transfer a little amount of money to you via PayPal.

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Another contented driver of the e55 model who created an account only to express gratitude to the original poster.

Excellent article! Upon doing an online search using the Google search engine, this particular post was shown as a result. The queue was clearly out. It was a quick and short 30-minute solution. Thank you once again!

It is quite delightful to be working on a Mercedes-Benz vehicle after previously dealing with a BMW equipped with a six-cylinder twin-turbo engine.

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Highly helpful, thank you. As a very vigilant and inexperienced individual, there are two more points to consider. The pipe is rigid, not flexible. I may be lacking in understanding, but that was not immediately evident to me. Additionally, there is just a sizable jubilee clip securing the surge tank lid located at the rear of the engine. The casting seems to be quite sturdy, and first, I was unable to discern its method of connection.
I obtained two photos from an internet movie to provide a slightly altered viewpoint.


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Thank you so much, for composing this. A few weeks ago, I installed fresh valve cover gaskets and replaced the engine mounts. I saw a significant improvement in my well-being, but, today my vehicle began to have intermittent engine failure. The vehicle's performance was somewhat uneven after the installation of new engine mounts, and the shifting was not optimal. However, these issues were much improved after reconnecting the purge pipe. Your article was essential in helping me identify the issue, which I would not have been able to do otherwise. I am quite pleased with the outcome.

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