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There are a lot of useful threads about this common problem, but I would still appreciate help.

I have an R reg 2.5 TDI Caravelle (150K) with a Pierburg MAF Sensor.

About 4 months ago my van suddenly developed the standard problem that it had little power, especially above 2000 rpm. My (non VW specialist) mechanic immediately diagnosed the MAF Sensor as the cause of the problem. He simply disconnected it and power was restored.

I have to say that I have noticed very little difference in power or economy over the last 4 months with the MAF Sensor simply disconnected - I still average 35 mpg - but I work on the basis that some reasonably well paid engineers work for VW and they put the MAF Sensor there for a reason. So I kept a look out for a secondhand one.

I finally found one last week on ebay and it arrived looking virtually unused. It was in the original Pierburg box and it was described as "a spare used for diagnostic purposes" - which I believe.

Anyway, I fitted it yesterday, connected up the 6 pin plug and found myself back to exactly the same problem I had 4 months ago. I have now disconnected my nearly new replacement Pierburg MAF Sensor.

Any ideas?

1. It could be that the replacement MAF Sensor has also failed.
2. If that were the problem, are there tests that (say) a generalist auto-electrician can do to establish if that is the explanation. Would an auto-electrician know what measurements to expect from a functioning MAF Sensor, or do you really need a VW specialist?
3. Rather than the MAF Sensor being the problem, might a problem with the wiring be the cause? Any ideas on how to check for that?
4. As I believe that one type of MAF Sensor uses a "Hot Wire" system, it might be that things are protected by a fuse, and that may simply have blown 4 months ago. However the VW Owners Manual list of 35+ fuses doesn't seem to mention a specific one. Fuse no 15 - Engine Electronics (10A) probably covers it and a lot else besides. Could it be a fuse?
5. Or any other suggestions? I suppose borrowing a working MAF Sensor from a friend with a 2.5TDI would be one answer if I knew anyone who didn't mind me dismantling parts of their engine!

Any help/suggestions much appreciated.
 

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i have 54 t5 2.5 130 bhp recently hesitated at 1800 revs lots of black smoke down on power cleaned egr no better unplugged maf ran fine no smoke but down on power new maf no better new allard delete pipe fitted runs like new bus learn from my mistakes don't buy maf
 

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can be checked via vagcom, details on the site somewhere..
disconnecting the MAF results in a circuit fault which puts the engine into a limphome mode which defaults a number of settings within the ECU, this can also have the effect of masking the actual fault on the van.
Quite often the MAF is not at fault.

Also check for wiring snapped within plastic trunking over top of engine - wiring failures are the most common faults on all engine management systems, sensors are far more robust.

Your mechanic would have needed vagcom or similar to diagnose the MAF fault, else he is pi55ing in the wind at your expense.
 

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I was down in power in my old 2000 2.5, so i changed air mass sensor and the thing took off. Unfortunately i have snails coming past me again. Nightmare. any ideas
 

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check the fuse at the top of the fuse panel, the one's nobody knows what they are for.................................
 
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