A buddy of mine has a 2000 E430 with about 105,000 miles. The check engine light came on, but the car ran just fine. His wife took the car to the dealership and they called to notify him the MAF was bad. Replacement parts were available and it could be fixed in a few hours, but a MAF replacement costs $500 or so.

He had it done but got the old MAF back. He says it looks visually fine, no dirt or other evidence of physical damage. Is there a way to check these out, out of the car? What typically fails? Thanks, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

The MAF has a heated film. There is never any damage you can see but eventually enough contaminents land on the film so the sensor can't give an accurate reading of air flow (starting at high airflow and slowly working down the range usually). The engine light comes on because the O2 sensor are detecting that they need to trim the fuel mixtures outside the normal range (because the mixtures are getting leaner due to MAF fault).

It's still giving a measurement, but the measurement is slowly getting inaccurate......the o2 sensors can pick this up, the ecu can't detect without another sensor giving a conflicting reading.

__________________
Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32

I'm in the midst of an air mass sensor experiment. The check engine light came on on my 94 E320 - the idle would fluctuate from normal up to about 1200 rpms, pulled a code 10 from the DM plug and a code 4 from PIN #8. Disconnecting the plug resulted in exagerated symptoms. Putting in a known to be good sensor eliminated the problem immediately. So in short - the air mass sensor clearly had failed. I tried cleaning it - with electrical contact cleaner - put it back in the car, same problems. Then took it to a jewelry store and had it ultrasonically cleaned (something discussed in another post here) - put it back in the car, car has now worked fine for a week. It operates just as it does with the good sensor in the car. So to me the conclusion is pretty clear - an air mass sensor can fail just because it gets dirty, and ultrasonic cleaning can bring it back. What I don't know at this point is how long it will now last - a few more weeks or a few more years. But ultrasonic cleaning would seem to be at least an emergency measure, to get you back on the road - and perhaps more than that. I don't really know anything about an E430 - whether it's the same technology or not. If it's similar, installation should be a few minutes, not a few hours.

Deanyal,

I had the same codes (10 on the DM/4 on the LH-SFI) on my 94 E500 although it didn't have the symptoms you described as my car idled and ran fine. I also replaced the MAF but the CEL came back (same codes) only after a few weeks. As of now, these are the only codes stored and nothing else on the other modules. I'm leaning towards replacing the wiring harness but that was just replaced at 43k miles (under MB goodwill) according to the VMI and the car currently only has 76k right now. I don't know if I should take the plunge as the harness is almost 500.- or should I check for anything else? As you know, code 4 indicate high or low voltage at MAF or short circuit? Would a bad O2 sensor cause this problem too as old sensors tend to give lean readings and the LH-SFI, trying to richen the mixture is probably operating above it's normal range thus causing high/low volatage? Any other ideas. Thanks.

WDV

Thanks guys! I will see if that works here too. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

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What was the cleaning agent/s ????????