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Discussion Starter #1
Hi All,

My 2.0 156 has developed a problem.

Very bad throttle response, awful running at idle.

Plugged it into my PC,

Error P0100
Fault Component Code - Air Flow Meter
Fault Symptoms - Short Circuit Gnd / Open Circuit

I have unplugged the MAF, and the car still runs badly, the MAF was replaced back in December with a Genuine Bosch unit.

I have carefully cleaned out the throttle body, and checked for cracks in the ducting.

The only thing strange is when on the diagnostic software...

The air flow meter is reading air flow, but when you ask it to measure the Voltage reading from the Air flow meter voltage remains zero?? Should there be a reading??

Any help would be much appreciated.

Thanks
Graham
 

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Apparently there should be a voltage. My codes app shows P0100 as circuit A fault. Have a look at this:-

Part 2 -The Basics of Testing a Mass Air Flow (MAF) Sensor

From what I can see from the circuit diagram of a MAF in my GTV workshop manual it works on the principle of a Wheatstone bridge so there should be a p.d. I found this:-

https://books.google.co.uk/books?id=nkdNPpNqHpEC&pg=PA366&lpg=PA366&dq=airflow+meter+wheatstone+bridge&source=bl&ots=HTeSpQWzed&sig=bqkVQ5RivBEpXw1qx35qLrEnFeo&hl=en&sa=X&ved=0CD0Q6AEwA2oVChMI05PJrfqOxwIVA4HbCh1FkQ4q#v=onepage&q=airflow meter wheatstone bridge&f=false
 

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Discussion Starter #4
Thanks armoore, i will have a try at testing the MAF tonight then.
Do we know which Pin's are which on the 5 pin plug/MAF?
 

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Thanks armoore, i will have a try at testing the MAF tonight then.
Do we know which Pin's are which on the 5 pin plug/MAF?
I may be able to send you the page from the w/shop manual. Give me a moment. All in the manual are four pin, TS and V6s.
UPDATE:
However, on looking further into the manual some wiring diagrams do show a 5 pin MAF and plug but no internal details of the MAF. this says pin 1 not used on some vehicles with a Bosch MAF.
http://www.auto-consulting.it/DWN/Mass_Air_Flowsensor.pdf Also this one for VW but it gives some insights and a "how to". http://easyautodiagnostics.com/vw/1.8L/maf-sensor-tests-1
 

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Discussion Starter #6
Thanks for all the help armoore, I will have a look through the links in detail when I am home from work.
See if I can locate the problem.

Thanks Again :thumbup:
 
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