W176 1.5cdi Mass Air Flow Sensor Replacement

[divettri]

Hi all, I had my vehicle serviced at my local mechanic. This included a new Air Filter. Since this service, the Engine Management Warning has been illuminated. I took it back to the same mechanic who plugged it into the diagnostic machine & the fault that came out was Mass Air Flow Sensor. They re-checked the Air Filter (which was ok), took the inlet manifold off & checked the Mass Airflow Sensor which seemed ok & also checked & cleaned the electrical connections for the sensor before resetting the fault code. They said to drive it down motorway for one junction & back keeping in a low gear as could also be related to DPF blocking. I done this & all was ok until just before I got home when the warning came back up. I took it back immediately & it was same fault, Mass Airflow Sensor.

What I am wondering is whether it is easy enough for me to replace this myself to avoid any more costs (have paid out a lot already)?
How or where do i get the correct part?
Does anyone have a guide as to how to remove the old & fit the new?

Thanks
Ricki

 

[OneForTheRoad]

If it was totally fine before the service, I'd suspect the garage has upset something, did they tell the car the air filter was changed ? It's maybe seeing too much air and doesn't like it ( intake manifold leak ) . Mafs are known to recalibrate after driving so many miles ,so it may self fix , but the mil coming on suggests it's more than that .

A new maf might set you back upto £400 for mb part.

 

[BlackC55]

I have not ever replaced one on that Renault engine. I would possibly get a second opinion.

 

[divettri]

Is it a co-incidence that on replacing the air filter with new, the air flow sensor has gone into fault?

There is some suggestion online that it could be due to the fact that the old filter may have been so dirty that the new one has caused an "offset" in the expected airflow which is the fault & a new air filter routine needs to be done using a diagnostic tool to basically tell the ECU to ignore the previous stored data??

 

[OneForTheRoad]

Is it a co-incidence that on replacing the air filter with new, the air flow sensor has gone into fault?

There is some suggestion online that it could be due to the fact that the old filter may have been so dirty that the new one has caused an "offset" in the expected airflow which is the fault & a new air filter routine needs to be done using a diagnostic tool to basically tell the ECU to ignore the previous stored data??

Isn't that what I said . Have they told the car it's been changed ??

 

[ALFAitalia]

Not sure why you would have too....the whole point of a MAF is to measure airflow.....so with a new filter it should just be measuring a little bit more.....but in reality it wont be as even a pretty blocked filter can flow all the air an engine needs unless its at the redline. To me its either faulty MAF.....or wiring to it.

 

[OneForTheRoad]

Not sure why you would have too....the whole point of a MAF is to measure airflow.....so with a new filter it should just be measuring a little bit more.....but in reality it wont be as even a pretty blocked filter can flow all the air an engine needs unless its at the redline. To me its either faulty MAF.....or wiring to it.

But you do or at least can as an option on newer vehicles. Otherwise the maf has to self learn and recalibrate itself for optimum fueling. If you go from a totally black hacky filter to nice clean new one . It's included on icarsoft scanners in the service menu.

 

[ALFAitalia]

I'm sure you are right.....but why would it need to recalibrate..and recalibrate what. It measures air quantity....which it can do no mater how much or little air there is (within reason). If the air filter gets blocked enough to affect flow to a great degree (unlikely) it will measure less air....you don't have to reset it for a dirty filter so why would you have to a for a new one. Not doubting what you said....just trying to understand.

Do you, as a professional, recalibrate the MAF when you service a car/replace an air filter @BlackC55 ???

 

[OneForTheRoad]

I'm sure you are right.....but why would it need to recalibrate..and recalibrate what. It measures air quantity....which it can do no mater how much or little air there is (within reason). If the air filter gets blocked enough to affect flow to a great degree (unlikely) it will measure less air....you don't have to reset it for a dirty filter so why would you have to a for a new one. Not doubting what you said....just trying to understand.

Do you, as a professional, recalibrate the MAF when you service a car/replace an air filter @BlackC55 ???

It's more of an adaptation if done on a filter change , if not done then it's calibration by the ECU over time. That's my understanding of it . All to do with correct fuelling and emissions Afaik. Watch the below video and educate yourself .

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[ALFAitalia]

Right.....so you dont HAVE to do it.....it might just take a little longer to auto calibrate than if you do when it should be right from the moment you turn the key....which still sound slightly BS....because every brand of air filter will flow slightly different and even individual ones from the same line wont be identical....so it will have to calibrate itself anyway. Still does not really answer my question about why something that just measures air needs to be reset to measure air.....its should just read slightly more air with the new filter......its only job is to measure variations in air flow!! Smacks of a car makers usual attempts at bonding you to a dealer to do your work to me. I wont be recalibrating after a filter though. Wonder how long it takes to be correct without calibration.....with modern fast ECUs you would have thought fractions of a second!!

 

[OneForTheRoad]

Right.....so you dont HAVE to do it.....it might just take a little longer to auto calibrate than if you do when it should be right from the moment you turn the key....which still sound slightly BS....because every brand of air filter will flow slightly different and even individual ones from the same line wont be identical....so it will have to calibrate itself anyway. Still does not really answer my question about why something that just measures air needs to be reset to measure air.....its should just read slightly more air with the new filter......its only job is to measure variations in air flow!! Smacks of a car makers usual attempts at bonding you to a dealer to do your work to me. I wont be recalibrating after a filter though. Wonder how long it takes to be correct without calibration.....with modern fast ECUs you would have thought fractions of a second!!

Ask blackc55 for his professional opinion. . I'm just a diyer that googles stuff .

 

[ALFAitalia]

Did that in post 8!

 

[divettri]

Isn't that what I said . Have they told the car it's been changed ??

Sorry yes I think that's what you said.

As an answer, I don't know if they have told the car its been changed. Not sure if they'd know how to?? How can I explain this to them in the best way so they can understand?

 

[divettri]

Surely though even if a calibration was required or whether the ECU will self calibrate, there would be no reason to illuminate the Engine Management Warning?

 

[OneForTheRoad]

Surely though even if a calibration was required or whether the ECU will self calibrate, there would be no reason to illuminate the Engine Management Warning?

That's my train of thought. If it was fine before they touched it .