C-Max 1.6TDCi MAF Sensor - Ford C-Max Forum
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post #1 of 2 Old 07-22-2011, 04:26 PM Thread Starter
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Join Date: Jul 2011
Location: Coventry
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I'm looking for information ref MAF Sensor signal wire voltage, with sensor disconnected and ignition switched on. Scan result DTC P0103 Mass airflow high(119.41grams/sec) voltage on signal wire, pin 5 on connector, is 1Volt below battery voltage. Trying to decide if this correct I thought it might be 5Volts coming from the PCM. Trying to decide if it is a PCM failure or sensor failure or what!!
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post #2 of 2 Old 12-01-2011, 12:39 PM Thread Starter
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I have now resolved the problem. The MAF sensor fitted uses a nominal signal voltage of 12V which should be present at pin 5 when sensor is disconnected. The pin outs on the sensor are as follows-in1 IAT sensor signal nominal 7V.pin2 Ground.pin3 not used.pin 4 battery voltage.pin 5 MAF signal nominal 12VIf the above readings are obtained with connector disconnected and ignition on then the sensor is at fault.With ignition on, engine running the sensor puts out a frequency of 5000hz at idle. The pulse width widens with acceleration, i recorded 900hz at 3000 rpm as a guide.
Changing the MAF sensor in my case improved fuel consumption considerably. I discovered that the MAF was reading high by checking with a scan tool after the MIL light came on. I had no performance deterioration at all and the fault may have been there for some time before the MIL light came on.I noticed that oil was getting into the inlet tract from the engine breather, this had contaminated the MAF sensor and the air cleaner element. Cleaning the sensor with IPA had no effect so it had to be replaced. I have now modified the engine breather to prevent further contamination. So hopefully all will be well.

2005 Focus C-Max 1.6TDCi LX
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