P0101

Code P0101, Mass Air Flow (MAF) Sensor Circuit:

Mass Air Flow (MAF) Sensor Circuit Schematic:

CIRCUIT DESCRIPTION
The Mass Air Flow (MAF) sensor measures the flow of air which passes through it in a given time. The PCM uses this information to monitor the operating condition of the engine for fuel delivery calculations. A large quantity of air movement indicates acceleration, while a small quantity indicates deceleration or idle.

The MAF sensor produces a frequency signal which cannot be easily measured. The sensor can be diagnosed using the procedures on this chart.

DTC PO101 WILL SET WHEN:
^ Engine running.
^ No MAF signal for over 4 seconds.

ACTION TAKEN (PCM will default to):
With DTC PO101 set, the PCM will use a default value for air flow based on throttle position, IAC counts, and engine speed and some vehicle performance will return. The MIL (Service Engine Soon) will he illuminated.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step checks to see if PCM recognizes a problem.
2. A voltage reading at sensor harness connector terminal "A" of less than 4 or over 6 volts indicates a fault in CKT 492 or poor connection
3. Verifies that both ignition feed voltage and a good ground circuit are available.


DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, mis-routed harness, rubbed through wire insulation, or a wire broken inside the insulation.
Check for:
^ Poor connection at PCM pin - Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

^ Mis-routed harness - Inspect MAF sensor harness to insure that it is not too close to high voltage wires, such as spark plug leads.

^ Damaged harness - Inspect harness for damage. If harness appears OK, observe Tech 1 while moving related connectors and wiring harness. A change in display would indicate the intermittent fault location.

^ Plugged air intake filter - A wide open throttle acceleration from a stop should cause the MAF reading on the Tech-1 to range from about 4-7 gm/s at idle to 100 or greater at the time of the 1-2 shift. If not, check for restriction.