MikeKerr7

Recently purchased a 2003 S500 4matic with 95k miles. While a local indie mechanic test drove the S500, it cam back running like crap. He did not try to identify the problem, I assume he went and beat the crap out of it during the test drive, I had driven the car 2k miles including 1k in the pouring rain and no engine related issues.

I pulled the codes on my little i-car scanner and the following code came up "P2004 B2/5 (Hot film MAF sensor)". Order a new Bosch replacement (only $100 at Amazon with instant coupon). Pulled the old maf and discovered a Chinese clone MAF was installed.

After placing the new MAF, the car takes quite a lot of cracking to start. Test drove it yesterday no problems and no codes. Went to get some lawn mower gas, and .5 miles from home the S500 died on a slight incline. I let it roll back into a parking lot, restarted the car, and then went home and pulled codes. Same P2004 B2/5 (Hot film MAF sensor) error appeared.

Any thoughts on what is going on? I heard some oil getting on some wires can cause issues- but I don't know where to start to look for the location of oil on wires.

ibeforreal

When you say the car takes quite a bit of cranking to start I would replace the crankshaft position sensor.

cybertronicify

The MAF sensor is a very delicate piece of equipment. It has only has one piece of wire that gets heat up, and the computer will use that to measure the airflow. Dirt, oil, or anything that sticks to the sensor will make it run hotter, thus making your air/fuel ratio go out of balance. A dirty air filter will also cause dirt and debris to stick on the sensor. You can try to get the new sensor replaced, or use some MAF sensor cleaner. Like this CRC one from Autozone. Use nothing but MAF sensor cleaner, or it will damage it.

http://www.autozone.com/miscellaneou...ner/36011_0_0/

CPS issues will usually appear when the engine is hot. It will start up just fine and run until the engine gets hot. I have seen cases where it doesn't start even when cold.

engindin

I want to do my MAF cleaning also but unfortunately i can't find any CRC MAF cleaner around. So i was planning to use Contact Cleaner from WD40. I am scared now, cyber, are you sure it will damage it?

cybertronicify

You cannot use anything else other than MAF Sensor cleaner. They are chemically different and some contact cleaners even degrade plastic. WD40 CC has a oil based protectant, while good for your switches; it will destroy the MAF sensor. What country are you from? S320L, you might be from out of the USA.

This guy from UK ships to worldwide.

http://www.ebay.co.uk/itm/CRC-AIR-SE...item19ebc35519

A bottle of MAF cleaner is cheaper than a damaged MAF sensor. Careful with spraying down the sensor, don't let any dirt or grime get on the sensor itself. Give it 15-20 short bursts of cleaner and let it fully dry before attempting to power it up, or else the wire will burn and cook the cleaner into the wire.

ibeforreal

Agree with Jason, I wouldn't try anything but certified MAF cleaner.

MikeKerr7

I replaced the MAF, still have the problem. I have a new crankshaft position sensor arriving today, but the problem happens when cold; all the research indicates CPS problems occur when engine is hot. I will update results after CPS is changed.

CLK500 TWINS

I pulled the same code/description off my s55 amg today. I had an issue with the car running too rich at idle. Replaced the maf with a genuine bosch and then had a P0100 Maf circuit a code (ran at an auto parts store). Its been about 2 weeks and a blizzard later. Car runs fine in comparison to what it was doing. Idle is smooth with an intermittent vibaration. Acceleration is 4 times more responsive. Only things Im noticing are: a sometimes slight and other times obnoxious virbation in reverse and it doesn't start right up with a turn of the key. It starts, everytime, but I feel like it takes it a couple of seconds to catch as opposed to turn key-vroom.

Was able to get it back to my guy today and he pulled the same P2004 code with the Maf hot film description. He looked for the butterfly piece on the intake manifold but ita not throwing an intake manifold actuator desription. We're at a loss.