M271 p0172

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2006 - 2016 Mercedes Diagnose & Replace Mass Air Flow Sensor

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P0170 - Fuel Trim Malfunction Bank 1

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Thread starter Rustyboy Start date Jun 9, Tags ecu failure m Rustyboy New Member. Hi everyone. I thought i had previously posted on this problem but can now not find the thread.

I don't know if it was removed or i just dreamed i had posted it.We recommend Torque Pro. Your engine needs to put in the right amount of fuel for the amount of air coming into it, that is, the proper air-fuel ratio, to deliver the best power and fuel economy.

As suggested by the names, the HO 2 S is sensitive to oxygen O 2 content in the exhaust, which has a direct relationship to air-fuel ratio. On combustion, some of the oxygen in the air is used to oxidize the fuel, leaving a small amount in the exhaust, which the HO 2 S measures, sending a signal back to the ECU. If there is a lot of oxygen, this means that the engine is running lean, that is, not enough fuel was injected. Conversely, if there is very little oxygen, this means that the engine is running rich, that too much fuel was injected.

On the other hand, engine problems, such as high fuel pressure, a skewed MAF signal, or a faulty fuel injector, may dump in more fuel than required, or misreport how much air is entering, resulting in a rich condition.

m271 p0172

Depending on year, make, and model, DTC P may have number of causes. Here are some of the most common. Depending on the nature of the failure, DTC P may or may not be accompanied by drivability issues. On the opposite end of the scale, you may note rough idling, lack of power on acceleration, even misfiring or stalling, which tends to get progressively worse as the engine warms up. Particularly bad cases may be accompanied by black exhaust smoke and a blinking MIL, alerting you to possible catalytic converter damage.

You may also smell a strong fuel odor and see black soot in the exhaust tip or the back of the car, an indicator that a lot of unburnt fuel is making it through the system. Pro Tip: Before diagnosing fuel trim problems, it does one well to note that the Fuel Trim Monitor will not run unless the HO 2 S monitors have run and passed first.

The fuel trim monitor uses the oxygen sensor to run, which means that fuel trim codes are not oxygen sensor codes. This site uses Akismet to reduce spam. Learn how your comment data is processed. Hello,so there i have got vw polo 1. Check voltage on the Lambda sensor.

If it sticks, you have a faulty sensor. Make sure you have proper fuel pressure, about 36 psi at idle, up to 45 psi with the fuel pressure regulator vacuum line disconnected. If pressures are off, you may have a defective regulator or a poor vacuum source.

Turn the engine off and make sure fuel pressure stays stable. If it drops, you may have a leaking fuel injector. I have a Hyundai accent 1. I replace the coil packs back in December but they went out a month later I had to replace those as well.This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation.

Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. This can mean a negative fuel trim or a positive fuel trim has been detected.

The powertrain control module receives a signal from the oxygen sensors and will adjust the amount of fuel the engine receives based on the readings provided by the oxygen sensors. This action carried out by the powertrain control module is called a fuel trim.

If the signal from the oxygen sensors calls for less fuel, the powertrain control module will act out a negative fuel trim.

M271 Ecu failure

If the oxygen sensors call for a fuel increase, the powertrain control module will act out a positive fuel trim. Any condition that causes the engine to run lean such as a weak fuel pump, a clogged fuel filter, or a faulty fuel pressure regulator. Any condition that causes the engine to run rich such as a mass air flow sensor, manifold absolute pressure sensor, or a faulty fuel pressure regulator.

Symptoms of this code may vary depending on the vehicle and other conditions that are present. Some symptoms that may occur include:. A mechanic may diagnose this trouble code by using an OBD-II scanner to make sure that no other codes exist. If any other codes are found, they may be causing this code to occur. If this is the case, the causes of any other code must be found and resolved first. This may include checking the engine for any issues that may cause it to run lean or rich and repairing them before moving forward.

After the repairs are made, the mechanic would reset the Check Engine Light and run the engine. If the Check Engine Light came back on with a P code, then another problem exists. This problem is likely a powertrain control module if no other issues exist. Some people may look online and find that one of the most common causes of this code would be the mass air flow sensor. Once this information is found, the owner of the vehicle may decide to just replace the mass air flow sensor.

It is always important to have engine issues diagnosed by a certified mechanic who follows the correct diagnostic procedures. The P code can range in seriousness.The mass air flow sensor MAF is used to measure the amount and temperature of air that is entering the engine at any one time. The MAF also incorporates an internal intake air temperature sensor which measures the temperature of the intake air. The first indicator that you might have a problem with the MAF is the presence of a check engine light CEL on your dashboard.

The check engine lamp can be caused by a wide variety of problems with the engine: you need to read the codes from the computer to get a starting clue as to what the problem is. However, the engine will not be operating at peak efficiency, and you will most likely experience a loss in power and a decrease in gas mileage as a result.

It's best to get the problem taken care of relatively quickly, as running the engine in this condition can potentially cause damage to other components like the catalytic converters. Vacuum leaks and other air leaks in the system can cause MAF sensor errors. If you have a crack or leak in your air intake downstream of the sensor, then the MAF will be sensing less air than the engine is actually receiving.

You should carefully inspect all of your hoses, clamps and intake tubes for air leaks prior to replacing the sensor. You will need to remove the engine covers and air intake ducts to perform this work. Please see our article on replacing your air filters. The new MAF comes complete in the air body housing so you will have to remove the complete housing to replace it. This article also shows you how to remove the sensor from the housing to clean it. Make sure you only clean it with MAF sensor cleaner and that you never touch the sensor face with anything or you will destroy it.

With the air filter covers off you can see the MAF sensor housing at the rear of the engine red arrow along with the harness yellow arrow.


Large Image Extra-Large Image. Disconnect the harness red arrow by squeezing the two clips together and pulling it from the housing. Use a flat head screw driver and release the clip red arrow that holds the sensor housing to the intake manifold yellow arrows. Slip the mount off the housing. Here you can see the center clip red arrow and the clips that hold it to the manifold yellow arrows.

Wiggle the housing off the end of the throttle body. You will have to disconnect the breather tube red arrow to remove it from the engine.My car has been acting weird recently.

It idles roughly sometimes violentlyconsumes loads of fuel and at times accelerates sluggishly. Before replacing the mass air flow sensortry replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor. It measures the intake flow rate by measuring a part of the entire intake flow.

Temperature of the hot film is controlled by the ECM a certain amount. The heat generated by the hot film is reduced as the intake air flows around it. More air, the greater the heat loss. Therefore, the ECM must supply more electric current to maintain the temperature of the hot film as air flow increases.

The ECM detects the air flow by means of this current change. The Engine Control Module ECM calculates the necessary compensation to correct the offset between the actual and the theoretical ratios. In case the amount of the compensation value is extremely large The actual mixture ratio is too lean.

After exactly 90 seconds after start up the engine fluctuates for a few seconds hunting for air, I get P, P and P code.

m271 p0172

MAF is fine and I checked for leaks. I have cleaned the throttle body and all that other pipes that goes to the throttle body. I have put a new pipe that goes from the air filter to the cylinder head cover. The car does not want to start now. What should be me course of action to remedy the problems? Appreciate your assistance! Jon RESPONSE Before replacing the mass air flow sensortry replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner.

Mercedes benz C Kompressor engine I need a diagram to show me all the sensors. Mercedes Benz C Kompressor engine I have cleaned the throttle body and all that other pipes that goes to the throttle body.Forums New posts Search forums. Media New media New comments Search media.

Members Current visitors. Log in Register. Search titles only. Search Advanced search…. New posts. Search forums. Everywhere Threads This forum This thread. Log in. Contact us. Close Menu. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Home Forums Technical Engine. Thread starter jzb Start date Aug 12, Tags c kompressor m p p w After few visits in workshops, I am counting for help from this forum.

In last few months I have: - cleaned second o2 sensor's plug oil in plug- replaced first o2 sensor, - changed broken vacuum hose in workshop, - changed chain and timing chain tensioner in workshop after that P began to appear- again reviewed vacuum hoses in workshop, - cleaned exhaust camshaft position sensor oil in plug Do you have any advices? Can you help me, please? Last edited: Aug 12, Do you get the fuel system related errors when running on petrol or LPG or both? SLKNick said:. You must log in or register to reply here.

This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register. By continuing to use this site, you are consenting to our use of cookies. Accept Learn more….When you think of a ten-year-old Mercedeswhat's the first thing you imagine?

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m271 p0172

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