Diagnosis question: How long does a MAF sensor last?
Discussion
Anyone know how long a MAF sensor might reasonably last?
My 2.5T S-Max has done 98k over 7 years.
Hesitates at light throttle and doesn't run particularly smoothly under boost either.
Having unplugged the MAF sensor she's running really nicely....
In my head that means it's either a bad MAF or an air leak after the MAF throwing the mixture off.
Can't find an obvious air leak.
Obviously the easiest way to check the MAF is to buy an new MAF... but I don't really want to throw £170 away.
My 2.5T S-Max has done 98k over 7 years.
Hesitates at light throttle and doesn't run particularly smoothly under boost either.
Having unplugged the MAF sensor she's running really nicely....
In my head that means it's either a bad MAF or an air leak after the MAF throwing the mixture off.
Can't find an obvious air leak.
Obviously the easiest way to check the MAF is to buy an new MAF... but I don't really want to throw £170 away.
NDT said:
Anyone know how long a MAF sensor might reasonably last?
My 2.5T S-Max has done 98k over 7 years.
Hesitates at light throttle and doesn't run particularly smoothly under boost either.
Having unplugged the MAF sensor she's running really nicely....
In my head that means it's either a bad MAF or an air leak after the MAF throwing the mixture off.
Can't find an obvious air leak.
Obviously the easiest way to check the MAF is to buy an new MAF... but I don't really want to throw £170 away.
Some cars might last a year, some 20 years. There is just no simple answer.My 2.5T S-Max has done 98k over 7 years.
Hesitates at light throttle and doesn't run particularly smoothly under boost either.
Having unplugged the MAF sensor she's running really nicely....
In my head that means it's either a bad MAF or an air leak after the MAF throwing the mixture off.
Can't find an obvious air leak.
Obviously the easiest way to check the MAF is to buy an new MAF... but I don't really want to throw £170 away.
Nick - you can buy some cleaning products that remove the contaminants that cause inaccuracy and that might be worth trying. But before you go replacing parts it might be worth diagnosing it at the dealer using the factory recommended equipment and process, just so that you know whether the fault is truly a sensor one and not a connector / harness / earth issue.
stevieturbo said:
Some cars might last a year, some 20 years. There is just no simple answer.
They don't always throw fault codes when faulty either 
to the OP'er you need to know how to interpret the voltage output on the scanner of choice get it checked at a reputable diagnostic workshop you could save a lot of money 
I also agree with trying to clean the sensor 1st like mentioned with carb cleaner 
Sardonicus said:
They don't always throw fault codes when faulty either to the OP'er you need to know how to interpret the voltage output on the scanner of choice get it checked at a reputable diagnostic workshop you could save a lot of money I also agree with trying to clean the sensor 1st like mentioned with carb cleaner Tried cleaning the sensor last year although I used electrical contact cleaner not carb cleaner.
It didn't change anything. Visually the hot film looked clean anyway.
Got a specialist diagnostic guy to come and check it out last year but he was utterly useless... and although he claimed to have checked the MAF (only at no load though) I just don't trust what he said.
GavinPearson said:
Nick - you can buy some cleaning products that remove the contaminants that cause inaccuracy and that might be worth trying. But before you go replacing parts it might be worth diagnosing it at the dealer using the factory recommended equipment and process, just so that you know whether the fault is truly a sensor one and not a connector / harness / earth issue.
Good idea - might check voltage and earth on the plugs before I do anything else.Not a big fan of our local Ford dealer - and they don't want to work on our car either as I got them to pull OBD codes (which I paid for) then didn't give them the repair work...
Perhaps you are already aware of this, but the OBD code indicates a symptom, not a fault. Additionally at startup there will usually be some self testing function.
It may well be that at 0 rpm the MAF gives the expected voltage, but at a higher load point the voltage at the PCM may be lower than expected. You might assume that it is the MAF, but it could be the feed, return or reference wire at fault. Or the connector. Or an earth.
In turn the PCM calculates airflow based on what seems to be OK (an in-range fault). So running is not optimal. But it's unlikely to set a code - it's in range.
Disconnecting the MAF will trigger a code - causing the PCM to adapt, possibly adding fuel and using the TPS to infer MAF. If the car runs better you might think the problem is the MAF, but it could be the wiring. Swapping the unit is a way to test this, but a bit hit or miss and expensive with it.
Typically the way to diagnose these faults is to pull then clear codes, then follow pinpoint tests which should diagnose the problem. This will typically involve measuring voltages etc.
Independent guys typically don't have access to this information. The main dealer does. But clearly if your local dealer isn't cutting it for you then the best thing to do is go to a dealer that does, in case the independent's philosophy is to fix things by changing everything they touch whether the car needs it or not.
I often hear people say "but it fixed the car" when taking about major unit replacement, but that is senseless when the fault was fixable for literally hundreds or thousands less.
It may well be that at 0 rpm the MAF gives the expected voltage, but at a higher load point the voltage at the PCM may be lower than expected. You might assume that it is the MAF, but it could be the feed, return or reference wire at fault. Or the connector. Or an earth.
In turn the PCM calculates airflow based on what seems to be OK (an in-range fault). So running is not optimal. But it's unlikely to set a code - it's in range.
Disconnecting the MAF will trigger a code - causing the PCM to adapt, possibly adding fuel and using the TPS to infer MAF. If the car runs better you might think the problem is the MAF, but it could be the wiring. Swapping the unit is a way to test this, but a bit hit or miss and expensive with it.
Typically the way to diagnose these faults is to pull then clear codes, then follow pinpoint tests which should diagnose the problem. This will typically involve measuring voltages etc.
Independent guys typically don't have access to this information. The main dealer does. But clearly if your local dealer isn't cutting it for you then the best thing to do is go to a dealer that does, in case the independent's philosophy is to fix things by changing everything they touch whether the car needs it or not.
I often hear people say "but it fixed the car" when taking about major unit replacement, but that is senseless when the fault was fixable for literally hundreds or thousands less.
Sometimes MAF problems are almost impossible to identify the problem is so small...even if it is an apparent running problem.
And often aftermarket replacements are just as bad as faulty ones. Always buy genuine branded parts when it comes to airflow meters.
Doesnt specifically have to be dealer, but if it's Bosch, only replace with the correct Bosch etc
And often aftermarket replacements are just as bad as faulty ones. Always buy genuine branded parts when it comes to airflow meters.
Doesnt specifically have to be dealer, but if it's Bosch, only replace with the correct Bosch etc
One thing relevant to the lifespan of a MAF, aftermarket filters can cuss some serious issues, especially if they are oiled, the oil will wet and contaminate the surface of the MAF and hamper it's ability to do its job. A clean with isopropyl alcohol will sometimes return it to GWO.
Dave
Dave
GavinPearson said:
Perhaps you are already aware of this, but the OBD code indicates a symptom, not a fault. Additionally at startup there will usually be some self testing function.
It may well be that at 0 rpm the MAF gives the expected voltage, but at a higher load point the voltage at the PCM may be lower than expected. You might assume that it is the MAF, but it could be the feed, return or reference wire at fault. Or the connector. Or an earth.
In turn the PCM calculates airflow based on what seems to be OK (an in-range fault). So running is not optimal. But it's unlikely to set a code - it's in range.
Disconnecting the MAF will trigger a code - causing the PCM to adapt, possibly adding fuel and using the TPS to infer MAF. If the car runs better you might think the problem is the MAF, but it could be the wiring. Swapping the unit is a way to test this, but a bit hit or miss and expensive with it.
Typically the way to diagnose these faults is to pull then clear codes, then follow pinpoint tests which should diagnose the problem. This will typically involve measuring voltages etc.
Independent guys typically don't have access to this information. The main dealer does. But clearly if your local dealer isn't cutting it for you then the best thing to do is go to a dealer that does, in case the independent's philosophy is to fix things by changing everything they touch whether the car needs it or not.
I often hear people say "but it fixed the car" when taking about major unit replacement, but that is senseless when the fault was fixable for literally hundreds or thousands less.
Thanks.It may well be that at 0 rpm the MAF gives the expected voltage, but at a higher load point the voltage at the PCM may be lower than expected. You might assume that it is the MAF, but it could be the feed, return or reference wire at fault. Or the connector. Or an earth.
In turn the PCM calculates airflow based on what seems to be OK (an in-range fault). So running is not optimal. But it's unlikely to set a code - it's in range.
Disconnecting the MAF will trigger a code - causing the PCM to adapt, possibly adding fuel and using the TPS to infer MAF. If the car runs better you might think the problem is the MAF, but it could be the wiring. Swapping the unit is a way to test this, but a bit hit or miss and expensive with it.
Typically the way to diagnose these faults is to pull then clear codes, then follow pinpoint tests which should diagnose the problem. This will typically involve measuring voltages etc.
Independent guys typically don't have access to this information. The main dealer does. But clearly if your local dealer isn't cutting it for you then the best thing to do is go to a dealer that does, in case the independent's philosophy is to fix things by changing everything they touch whether the car needs it or not.
I often hear people say "but it fixed the car" when taking about major unit replacement, but that is senseless when the fault was fixable for literally hundreds or thousands less.
Car hasn't thrown any codes (frustratingly) apart from when I disconnected the MAF.
Cleaned the sensor and she's still hesitating.
Will check wiring tomorrow.
Shame that my experience with a so-called speacialist was so bad... I lost faith when he started speculated that the EGR and variable geometry vanes were the cause of the problem... neither appear to be present on this engine.
I think it's either a duff MAF or an air leak.
DVandrews said:
One thing relevant to the lifespan of a MAF, aftermarket filters can cuss some serious issues, especially if they are oiled, the oil will wet and contaminate the surface of the MAF and hamper it's ability to do its job. A clean with isopropyl alcohol will sometimes return it to GWO.
Dave
thanks Dave.Dave
Stock filter all its life.
Did the isoprop clean this morning.
Nick
most factors wont accept returned maf sensors if they have been out of the sealed bag , i keep a few known good ones for the common stuff as its pretty much the only way to prove a duff maf once the wiring checks out . main agents will just bang a new one on to see if it cures it before going any further
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