Mass air flow sensor replacement -Do it yourself job?

[abg321123]

I have a 99' CLK 430. The Mercedes dealer wants to charge me 300 dollars to change a 80 dollar mass air flow sensor Question is, can I do this myself and save a bit of money or is this a professionals job?
I could use a little help. I think this sensor is located on the topside of the manifold where the engine cover/air filter holder meets the manifold. Just snap out the old one and in w/ the new!!

 

[Messa]

I am by no means an expert, but on all the cars I have had, that have had airflow sensors, they are removed by either unscrewing (like a spark plug) or unclipping, by some sort of retaining spring, and of course disconnecting the wiring from the loom.

I would certainly try it myself if i were you.

Messa

 

[piestore]

air mass

Hi

Yes this is a very easy DIY job , pull of the air filter housing unclip the air mass metre one at the top and another at the base, unplug the conection and rebuild,

But if this doesn't fix it your on your own. If the dealer had done the job he now has to sort at no extra cost

 

[jberks]

I was under the impression that whilst the manual act of changing the MAS is very easy, the ECU needs to be reset which requires specialist kit. Also, I am surprised at the cost of the component - the one for my E240 was around £250 and I would expect a 430 version to be more. $80 sounds extremely cheap and if true we have a great import opportunity ! I wonder whether the $80 is for the install and ECU reset and the $300 is actually the part ?

By the way, I tend to call it a MAS too, but isnt it actually an Air Mass Sensor (AMS)? Splitting hairs and I can't afford many so I'll shut up now

 

[Arnie]

The ECU should reset itself when it finds a working sensor. I can't really comment on MB prices, but as the sensor is essentially just a hot wire in (now) a plastic tube, with some simple electronics, $80 should not be too far off for a generic Bosch one.

 

[jberks]

Arnie,
agreed, it should be around $80, but the going rate appears to be >£200 at dealers and specialists. If anyone knows of any cheaper sources, I imagine many on this forum would be delighted to hear about it. I've also heard from a number of sources about having to get the ECU reset, including an entry on the invoice I believe. Anyone know whether this is actually needed or is it another cash cow activity ?

 

[abg321123]

Pardon me or being stupid..the ECU is what? My assumtion is it's the computer which trips the "check engine" light. So if I replace the sensor the light will go off automatically? Or will I need the dealer to do this for me?

 

[Arnie]

The ECU is the Engine Control Unit. I've not tried it with the latest engines, however, I know that some ECUs have a default setting in case of sensor failure and will continue to work, albeit not optimally (Eg 300E engines with Bosch KE Jetronic). Others which rely more heavily on this sensor (do not have a throttle-position sensor) will not run properly. However, all the ones I have tried will return to working normally, once the sensor is replaced or fixed. Most ECU's will clear stored fault codes relating to engine sensors automatically if they do not re-occur after 3 or 4 engine restarts, so a manual reset should not be necessary. In anycase, a reset is at most a 5-minute job and should not incur a great expense.

 

[abg321123]

Thanks..I'm on my way to my local dealer to pick up the sensor!! Let you know how it goes.

 

[abg321123]

Changed the Mass air sensor..which was 255.00 dollars, not 80.00. Check engine light stayed on but I unhooked the battery and re-connected it and that seemed to fix that light. BUT ...now the ABS light is on..how the hell do I fix this one?? Will it go off by itself?

 

[moveitall]

Hi abg321123,

If your ABS light is still illuminated then all you have to on my CLK230 is turn steering wheel lock-to-lock and the light should go out?
Let me know how you get on?

 

[moveitall]

The ECU is the Engine Control Unit. I've not tried it with the latest engines, however, I know that some ECUs have a default setting in case of sensor failure and will continue to work, albeit not optimally (Eg 300E engines with Bosch KE Jetronic). Others which rely more heavily on this sensor (do not have a throttle-position sensor) will not run properly. However, all the ones I have tried will return to working normally, once the sensor is replaced or fixed. Most ECU's will clear stored fault codes relating to engine sensors automatically if they do not re-occur after 3 or 4 engine restarts, so a manual reset should not be necessary. In anycase, a reset is at most a 5-minute job and should not incur a great expense.

Does anyone know if an AMS(Air Mass Sensor) fails on a 1999 CLK230 whether the dashboard light should come on?

 

[jimsinessex]

Moveitall,
Tha MAS failed on my 1999 CLK230K and no warning lights came on. The engine went into "limp mode", i.e. it wouldn't pull the skin off a rice pudding but I was able to nurse it to the Stealership!

Jim

 

[jberks]

Ditto - no lights or warnings on my E240 either ,just the same, only enough power to crawl to the garage. It seems the cars with a computer display keep quiet when the sensors fail.

 

[moveitall]

Thanks guys!
It cost me £400 to have it replaced by my local "stealership", I've written to MB UK for explaination as to why it failed after only 23000 miles, and how long the new one is warranted for?
Keep the comments coming!

 

[jimsinessex]

From other posts on here I now believe the MAS often fails due to contamination and can sometimes be successfully cleaned with carb cleaner or brake cleaner. If mine fails again I will certainly be trying this before forking out for a new one. I have seen similar comments about the Throttle Body which I have also had replaced by the Stealers!