P0103 Mass or Volume Air Flow Circuit High -- HELP!

[JonnyMac]

I need some advice. I've been getting a single code, P0103 (2012 boxer 2.2l) intermittently for the last month or so. I've been trying to resolve the problem before a planned trip to France in 8 days but I'm rapidly running out of ideas and time.

Symptoms happen very intermittingly, sometimes once an hour, sometimes twice in 10 mins.
40% of the time I'll get the engine management light on, a few times this also resulted in limp home mode until the error was cleared.
60% you'll just see the error in the ODB reader with no limp home mode or engine light on

What I've replaced

• New MAF sensor
• Soldered in a new MAF sensor connector
• New O2 sensor
• New alternator
• Added a second earth strap direct from battery to engine
• New rear number plate light housing( it was pretty crusty looking and they can apparently cause MAF issues because they share the same 12v power source)
• New Air filter

What I've checked

• There don't appear to be any air leaks around the air filter housing
• Original Engine earth strap was replaced last year
• There does not appear to be any damage to the cabling from MAF to ECU
• The MAF cable is not routed near anything electrical until it gets to the ECU
• Both MAP & MAF appear to show normal reading while at idle and getting revved

What I've checked with the engine running while watching the MAF live readings, trying to (unsuccessfully) generate the error.

• Shaking/bending the MAF sensor and its cable back to the ECU
• Shaking/bending the MAP sensor and its cable back to the ECU
• Shaking/bending the Water in Diesel sensor and its cable back to the ECU (shares power supply with rear number plate and MAF)
• Shaking/bending the ECU's earth cables behind the front bumper
• Cleaning and reseating the Connectors into the ECU
• Shaking the cables going into the BSi
• Shaking the ECU
• Removing the MAF from it's housing creates a significant drop in readings but no errors.

 

[PeterCarole29]

I read an earlier post that theres a sensor in the drivers wing mirror ?

 

[ivorantony]

There plenty of cloned MAF sensors out there, have you made sure yours is genuine and a reputable make? Preferably from the same manufacturer,

 

[JonnyMac]

I read an earlier post that theres a sensor in the drivers wing mirror ?

I seen that as well but I think it must be for newer vans, mine has never worked in the 4 or 5 years I've owned my van and you can still see the outside temperature on the ODB reader so it must get it from somewhere else.

There plenty of cloned MAF sensors out there, have you made sure yours is genuine and a reputable make? Preferably from the same manufacturer,

It's definitely a generic looking replacement MAF sensor but the original is OEM and i don't think they would both give the same fairly rare error?

 

[JonnyMac]

Oh, I've also disconnected the house battery's/solar from the van so both systems are 100% separate at the moment.

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[PeterCarole29]

I seen that as well but I think it must be for newer vans, mine has never worked in the 4 or 5 years I've owned my van and you can still see the outside temperature on the ODB reader so it must get it from somewhere else.


It's definitely a generic looking replacement MAF sensor but the original is OEM and i don't think they would both give the same fairly rare error?

Thats good

 

[the1andonly]

JonnyMac
If you replace the MAF sensor in a ducato you need to recode the new sensor to the ECU. also reset the codes. I the ecu thinks its the same MAF sensor it will continue throwing the error.
It's definitely a generic looking replacement MAF sensor but the original is OEM and i don't think they would both give the same fairly rare error?
if it thinks its the same Sensor it will.
If its the same engine as in a Ducato Multiecuscan should do the job else its Alfaobd on a windows laptop or android device. Cheap Generic readers are not upto the job. ps the MAF sensor also has a temp sensor.
Of course this may not apply to your engine

 

[JonnyMac]

Thanks but they do have different engines and i don't believe the Peugout has a specific reset sequence but I did have the battery disconnected for about an hour after I replaced it and I'm using a laptop and the Peugeot dealer software(cant remember the name) as a scan tool

 

[Gromett]

That rang a bell. I remembered seeing someone having a MAF problem, replaced it and it didn't fix. so he thought it was a vacuum leak. He used carb cleaner I think to detect a vacuum leak.
I just searched for the video but can't find it. Here is an alternative though. Not sure if it will help you but perhaps worth a go.

If the MAF sensor is good then vacuum leak seems the next likely candidate?

 

[Landy Andy]

I would certainly be removing and cleaning, if not replacing the MAP sensor as in my experience errors are caused by the two sensors not giving what is expected, as their reading are relative, and MAP sensors can often get gummed up. A good clean with brake cleaner is a simple process.

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[mitzimad]

That rang a bell. I remembered seeing someone having a MAF problem, replaced it and it didn't fix. so he thought it was a vacuum leak. He used carb cleaner I think to detect a vacuum leak.
I just searched for the video but can't find it. Here is an alternative though. Not sure if it will help you but perhaps worth a go.

If the MAF sensor is good then vacuum leak seems the next likely candidate?

good call using carb cleaner but im not sure if most cars stop if you remove the maf plug all those ive played with revert to basic map settings when removed

 

[Gromett]

Found the video. No wonder I couldn't find it. it was 12 years old lol.

 

[Gromett]

good call using carb cleaner but im not sure if most cars stop if you remove the maf plug all those ive played with revert to basic map settings when removed

I posted more as a demo of the vacuum leak detection method.

I will just say I am not a mechanic. It is the big subject right next to plumbing where no one should listen to me or consider anything I say on the subject useful

But as Wildbill can attest if a computer is involved I will have a pop and have ended up doing some jobs I didn't think I could do such as changing injectors etc.

I love diagnostics and problem solving though soo....

 

[JonnyMac]

Thanks for all the suggestions .
I definitely should have cleaned the MAP sensor, it looks to be reading ok but maybe its gummed up enough to cause an intermittent fault?
I've come across the vacuum videos on youtube but I think they are for petrol engine? my very very basic understanding is that my diesel engine just uses a vacuum pump for the brake master cylinder though im really not sure?

 

[Gromett]

I've come across the vacuum videos on youtube but I think they are for petrol engine? my very very basic understanding is that my diesel engine just uses a vacuum pump for the brake master cylinder though im really not sure?

Oh, Think that is a different thing?

I thought it was when the piston goes down it create a vacuum that pulls in air. I thought it was this vacuum that you are checking for a leak for. So if air gets in from anywhere BUT the air filter/MAF then it messes with the readings and causes the wrong amount of diesel to be injected?

Again I am not a mechanic so am probably misunderstanding this?

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[the1andonly]

good call using carb cleaner but im not sure if most cars stop if you remove the maf plug all those ive played with revert to basic map settings when removed

exactly what i thought.
as to carb cleaner i've seen Propane being used for same function.(Schrodingers Box)

 

[Wildbill]

I posted more as a demo of the vacuum leak detection method.

I will just say I am not a mechanic. It is the big subject right next to plumbing where no one should listen to me or consider anything I say on the subject useful

But as Wildbill can attest if a computer is involved I will have a pop and have ended up doing some jobs I didn't think I could do such as changing injectors etc.

I love diagnostics and problem solving though soo....

know nothing about computers and diagnostic
wildbill

 

[JonnyMac]

I'm definitely not 100% clear and could be talking nonsense but i think petrol engines create a lot more vacuum and its used for several different functions in the car inc fuel/air mixture and diesels engines don't. The only thing I can see in the workshop manual related to vacuum is the vacuum pump attached to the engine that runs the assisted brakes.

 

[Gromett]

know nothing about computers and diagnostic
wildbill

We made a good team diagnosing the injectors on my van that time Me getting the computer side sorted and shouting figures to you and showing you the graph.
You Fiddlesticksing about under the bonnet with cups of diesel and injector pipes loose you managed to diagnose/fix what a handful of other garages couldn't.

 

[Gromett]

I'm definitely not 100% clear and could be talking nonsense but i think petrol engines create a lot more vacuum and its used for several different functions in the car inc fuel/air mixture and diesels engines don't. The only thing I can see in the workshop manual related to vacuum is the vacuum pump attached to the engine that runs the assisted brakes.

The diesel engine works on the Suck Squeeze Bang Blow principle so when it sucks there must be a vacuum to pull in the air? Until the turbo kicks in and assists?

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[Gromett]

I'm definitely not 100% clear and could be talking nonsense but i think petrol engines create a lot more vacuum and its used for several different functions in the car inc fuel/air mixture and diesels engines don't. The only thing I can see in the workshop manual related to vacuum is the vacuum pump attached to the engine that runs the assisted brakes.

You made me second guess myself. I have checked and although you are correct that some modern engines don't create enough vacuum from the piston to power ancillaries and therefore have an extra vacuum pump. This is just as relevant to petrol engines as diesel apparently. Interesting read.

Here’s How To Check for Vacuum Leaks and Fix Them

Nope, finding them isn’t as hard as you thought.

www.thedrive.com

 

[Gromett]

Sorry for multiple posts. I am going through engine problems so looking at this type of stuff a lot at the moment.

My guess is your replacement MAF sensor is not up to spec and you are getting a similar but unrelated problem.
OR
You have a vacuum leak.

But as I say, I am not a mechanic and it is only my best guess.

 

[jockaneezer]

I think diesels don't create as much vacuum as petrol engines because they are "compression ignition" meaning they have to suck in a full cylinder of air to compress (heat) every stroke, or that cylinder won't get hot enough to ignite the fuel that's injected in, that's why older diesels at least, never had a "throttle" style butterfly valve on the intake to regulate the air flow like a petrol engine does, as they draw in variable amounts of air relative to their speed to keep the fuel/air mixture ratio correct ?
If you can remember vacuum operated windscreen wipers on older petrol cars, their performance used to tail off the faster you went (butterfly fully open) and produced maximum vacuum at tick over (butterfly valve fully closed).
Modern diesels have a vacuum pump fitted (might be on the end of the cam shaft or built into the alternator) to operate a multitude of things, such as variable vane turbos, brake assist servos and some Volvo's have it tied in to their fancy engine mounts.

 

[Landy Andy]

I think diesels don't create as much vacuum as petrol engines because they are "compression ignition" meaning they have to suck in a full cylinder of air to compress (heat) every stroke, or that cylinder won't get hot enough to ignite the fuel that's injected in, that's why older diesels at least, never had a "throttle" style butterfly valve on the intake to regulate the air flow like a petrol engine does, as they draw in variable amounts of air relative to their speed to keep the fuel/air mixture ratio correct ?
If you can remember vacuum operated windscreen wipers on older petrol cars, their performance used to tail off the faster you went (butterfly fully open) and produced maximum vacuum at tick over (butterfly valve fully closed).
Modern diesels have a vacuum pump fitted (might be on the end of the cam shaft or built into the alternator) to operate a multitude of things, such as variable vane turbos, brake assist servos and some Volvo's have it tied in to their fancy engine mounts.

All correct

 

[welshcake lady]

if in doubt, call your breakdown company out, the RAC carry excellent diagnostic machines.

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[Gromett]

I think diesels don't create as much vacuum as petrol engines because they are "compression ignition" meaning they have to suck in a full cylinder of air to compress (heat) every stroke, or that cylinder won't get hot enough to ignite the fuel that's injected in, that's why older diesels at least, never had a "throttle" style butterfly valve on the intake to regulate the air flow like a petrol engine does, as they draw in variable amounts of air relative to their speed to keep the fuel/air mixture ratio correct ?
If you can remember vacuum operated windscreen wipers on older petrol cars, their performance used to tail off the faster you went (butterfly fully open) and produced maximum vacuum at tick over (butterfly valve fully closed).
Modern diesels have a vacuum pump fitted (might be on the end of the cam shaft or built into the alternator) to operate a multitude of things, such as variable vane turbos, brake assist servos and some Volvo's have it tied in to their fancy engine mounts.

I agree. That article I linked also says this .

BUT. A vacuum is still created and is used to suck the air in for ignition. If the vacuum pulls air in from anywhere other than designed route it means that the MAF sensor will be getting a low reading. It will compensate and your vehicle will run lean as I read/understand it?

Please note. I am not stating this from any expert position. Just my reading of it.