Tip & How-To about Mercedes-Benz E-Class

MAF errors and how to fix

1.1b) Symptoms of faulty MAF:
Associated OBD2 error codes DTCs: P0100 - P0104 (Often P0171-P0174)

  • Idle 'Surge and slow': The idling engine often exhibits a rhythmic pattern of 'surge and slow' every two or three seconds when the MAF is at fault. In older cars the carbon track in the air vane MAF can wear through leading to errors in voltage signal to the ECU. In modern MAF sensors the delicate heated coil or film can become contaminated by dirt or simply break or burn out leading to an error or an absent signal.
  • Erratic idle/near stall: If the MAF gets dirty the signal indicates low air mass and the ECU responds by reducing the fuel mix to the engine to an extent that it struggles to maintain a steady idle or even to keep running.

How to check? Disconnecting the faulty MAF will halt the symptoms of 'surge and slow' and the engine will resume a steady idle which maybe higher or lower than usual. The ECU will take its signals from the throttle position sensor (TPS) to maintain the engine idle in the absence of MAF input. Visually inspect the MAF when it is out, as dirt residue will be easy to spot.
The MAF has 3 or 4 pins in its socket connector:-
3 pins: one is 'ground', one is 12 volt (or 5 volt) 'reference' and the third is 'signal'
4 pins: as above but additional 'hot wire ground'
The 'signal' pin should output about 1 volt at idle and nearer 5 volts at open throttle. If the output looks good but engine still reports bad MAF then check wiring continuity between plug connector and ECU.

How to fix? With the older variety of MAF, a possible fix consists of first running a knife around the silicone seal and opening the box unit, then easing the contact-arm body along the air vane shaft by a few millimeters and then bending the contact arm downwards to again make contact with a fresh concentric carbon track to that of the worn region.
For the modern hot film or hot wire MAF there are no moving parts. Dirt and oil carried in the air stream are the only hazards and this can be cleaned off by spraying with a residue-free electrical cleaner and allowing it to air dry; ideally direct contact with the MAF ought to be avoided as it is easily damaged, although a very gently wipe with a soaked cotton bud should be OK. If the MAF is beyond reviving through cleaning then it must be exchanged for new one.
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P0103 code. I cleaned maf still have same code and stalls. I disconnect maf still stalls. I changed it one year ago code come back after 4 weeks. I have 2000 Hyundai Elantra.

the ecm may be bad,
P0103 OBD-II Trouble Code Technical Description Mass Air Flow (MAF) Circuit High Input What does that mean? Basically this means that there is a problem with the Mass Air Flow High (MAF) sensor or circuit. A more technical description would be that the MAF circuit had higher than expected voltage (air flow). Other MAF sensor circuit DTC trouble codes are P0100, P0101, P0102, and P0104. Symptoms You will likely not notice any serious drivability problems, although there may be symptoms such as a general decrease in power or sluggishness. Causes A code P0103 may mean that one or more of the following has happened: The MAF may be disconnected, or a wiring connection may be bad The MAF sensor may be damaged The vehicle computer may be faulty (very rare) Possible Solutions The simplest thing to do is to reset the code and see if it comes back. Then start with the cheapest, easiest repair procedures: Verify that the Mass Air Flow Sensor wiring is connected properly and that there are no broken / frayed wires. Inspect for any air leaks near the MAF sensor. Take the MAF out and clean it using a spray cleaner such as brake cleaner or electrical contact cleaner. Be gentle with the sensor. Check the voltage of the MAF sensor (refer to a repair manual for vehicle specific information) Replace the MAF sensor. Register now to ask a question (free) Related P0103 DTC Discussions 2005 Duramax 6.6 P0103 help I have no clue where to begin looking for the solution to this code. Mass Air Flow (MAF) Sensor Circuit High Voltage is the description of the code, I've looked on various forums and i cant seem to find a definite cause. Ive cleaned the MAF several times with MAF cleaner. I seem to only get this c... 2002 Hyundai accent L 1.5 P0103 Put in a new MAF sensor but code still remains for MAF sensor high voltage. Using scan tool, the airflow rate=920 cf/m and the intake air temp reads -40?F at idle. Both readings are way out of the norm. Not sure what to do next, any ideas would be appreciated. P.S. I traced back the wires for MAF se... 2001 Mazda MPV p0103 & p0174 codes recently, this minivan has a P0103 & P0174 code. researched about the codes and MAF sensor seems like the common denominator between these 2 codes although according to Mazda, P0174 affected part is the fuel injection system where fuel trim system too lean while the 103 has the MAF as the part ... Corolla with MAF codes p0171 p0100 p0101 p0103 I have a 2000 corolla that I bought last fall. It had soft codes that didn't store. Now it has hard codes 0171, 0100, 0101, 0103. Today it started chugging and lurching during hard acceleration. I was a Toyota technician 10 years ago, but never really dealt with this particular model. It has 11... 2002 3.8L Pontiac GPX (P0172, P0101 and P0103) Hello, I have been having some rough starting, rough idle and stalling issues. I have printed off the P0172 page and started to replace items. Two weeks agao I got MAP codes. 1. So I replaced the MAP. It still had a stalling issue/rough idle. 2. So I changed the Idle control, PCV, cleaned my air fi...

Read more at: http://www.obd-codes.com/p0103
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May 30, 2015 | 2000 Hyundai Elantra

3 Answers

code p0171 and p0174

P0171 possible cheap fix

Feb 21, 2015 | 2002 GMC Sierra 1500

1 Answer

97 toyota surges at an idle

(which engine. ?????)_
as always check all fuses. and scan the ECU for DTCs. first.
there is no need to fix OBD2 cars like 1980 cars (hard rows to hoe)
it can be 2 problems this......
lets fix the easy one first. idle. (and hope for moving issues to fix for free) it idle car is parked, so is 100% safe tests. (not moving)

so it surges at idle.
1: hot or cold or both.?
2: low extreme RPM and high at idle.

400 to 800 RPM? surge.
1000 to 2000. what? numbers tell the tale.

first off, idle is the last thing to work right on any engine.

there are many ways to find what is wrong.
fix idle surge way.
i make sure that the engine holds closed LOOP status.
hot idle, if not , i fix that first.
keep in mind if not in closes loop and lean
all lean engine surge and guess what the ISC will add to the surge
because idle is way too slow, so the ECU open the ISC wider
and wider and its still too slow, so the ECU resets the ISC
this cause a worst hunt (surge)
the ECU adjust spark time and the ISC to get 800 rpm. (spec. look up yours)
so say , i see closed loop failed, OBD2 scan page 1
i look at the O2 sensor an its stuck lean.
if stuck lean and it really is (o2 bad?) then its lean and it will surge
1: i find 02 sensor bad, (only effects idle and light steady cruise)
2: i find fuel pressure at 15PSI , hopeless low .
3: i find all injectors clogged. and lean.
4: with MAF EFI, ( i find maf reading too low, (dirty) causing lean.
5: if MAP car, i find the MAP stuck hard high vacuum causing lean.
not knowing what engine you have or the idle hot surge range,
i can not go farther.

the driving bog tells me,
1: scan the ecu ,get DTCs; do that first.
2: clean MAF if car has one, ask how..
3: check fuel pressure.

my guess is engine is lean. and starving for fuel all the time.
cept WOT.

MAF cars starve for fuel if there are any vacuum leaks.
MAP cars do opposite, they race fast with 100% full power.
MAF is air density EFI
MAP is speed density EFI.
apples and oranges diffr. so what engine.

Jan 07, 2014 | 1997 Toyota Tacoma

1 Answer

Ford Taurus Engine Light is: P0171 & P0174. I am thinking a MAF Sensor

Could be a problem with the MAF sensor but if it is you should have a code for that too.
Other causes include low fuel pressure, and a vac leak or air leak in the intake hose to the MAF.
The codes mean the ECM can not make the injectors rich enough to make the O2 sensors switch back and forth.

Jul 29, 2012 | Ford Cars & Trucks

1 Answer

code 171 bank 1 system running to lean?

Hi there:
DTC P0171 - System Too Lean (Bank 1)
Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.

You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.

A code P0171 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor.

Possible solutions include:
In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure

On rare occasions, a check engine light may be experienced with DTC P0171, P0441, P0455, and/or P2420. These DTCs may be a result of an internal PCM driver issue that may keep the EVAP purge solenoid control circuit grounded at times instead of supplying a pulse width signal on the circuit. ask your dealer and check this TSB:
#PIP3621: DTCs P0171, P0441, and/or P2420 - Inspect Production Part Number on PCM - keywords CEL check ECM EVAP lamp lean light repeat trim updated - (Nov 9, 2005)
Subject: DTCs P0171, P0441, P0455 and/or P2420 - Inspect Production Part Number on PCM

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

Feb 29, 2012 | Cars & Trucks

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