MAF Sensor Causing CEL?

[Lee Quave]

The CEL on my 1999 996 C2 came on on the way back from the Porsche Parade in Charlotte. I received codes 115/P0102 mass airflow sensor Type 3; short to ground/below lower limit/lean mixture threshold and 108/P1602 voltage supply Type 2; open circuit/no signal.

I have a K & N CAI but I replace it with the stock unit this past Sunday. The CEL came on again just yesterday and I get the same codes. Prior to the trip I received error code P1123 and P1125 but they haven’t returned since going back to the stock filter setup. I think it may be the MAF sensor.

My questions are 1. Do MAF sensors go bad or deteriorate over time? I have the original sensor. 2. Are MAF sensors easily damaged? 3. Is there a test or an inspection procedure to tell if one is damaged? 4. Could a bad MAF sensor cause the error code P1602?

:renntech:

[Loren]

1. Yes, they seem to go bad or wear out.

2. Yes, they are a thin wire film sensor. They both get damaged and dirty pretty easily.

The egas cars got a new MAF that has a Z pattern that seems to help keeping the dirt out but older non-egas cars (MY99 C2) can not use those MAF's.

3. Yes, you will need to look at the air flow over the sensor, TRA and FRA. You will likely need the Durametric software, a PST2 or PIWIS to monitoer these readings.

4. No, not usually. P1602 says you disconnected the battery.

[Lee Quave]

1. Yes, they seem to go bad or wear out.

2. Yes, they are a thin wire film sensor. They both get damaged and dirty pretty easily.

The egas cars got a new MAF that has a Z pattern that seems to help keeping the dirt out but older non-egas cars (MY99 C2) can not use those MAF's.

3. Yes, you will need to look at the air flow over the sensor, TRA and FRA. You will likely need the Durametric software, a PST2 or PIWIS to monitoer these readings.

4. No, not usually. P1602 says you disconnected the battery.

Loren,

I have a Duramtric reader. What should the readings be for TRA and FRA?

Thanks for the quick response.

Lee

[Loren]

Set the tables and example below.

Remember that the MAF reading (air flow) should change with RPM - if it does not then chances are your MAF is bad.

[Hobbes]

I had a CEL. I checked for faults with durametric and found I had a P1128 - 02 Sensor bank 1. I cleared the fault and cleaned my MAF. No more CEL. But when I read the actual values and compared them to the tables above, I found something that doesn't come close to the numbers.

Hot film MAF Spec. rpm Adaption range 2 (FRA) bank 1 Adaption range 1 (RKAT) bank 1 Mass air flow sensor

14 700 1.02 -2.72 1.27

14 700 1.02 -2.72 1.27

14 700 1.02 -2.72 1.26

14 700 1.02 -2.72 1.27

14 700 1.02 -2.72 1.27

14 700 1.02 -2.72 1.25

14 700 1.02 -2.72 1.27

14 700 1.02 -2.72 1.27

14 700 1.02 -2.72 1.26

14 700 1.02 -2.72 1.26

My MAF sensor reading did change with an increase of RPMS, not significant (1.28/1.31). Anyone know what may cause these types of reading from the numbers i provided?

2000 996, 3.4

Thanks.