P0101

DTC P0101 MAF System Performance




Circuit Description
The mass air flow (MAF) sensor measures the amount of air which passes through it into the engine during a given time. The powertrain Control module (PCM) uses the mass air flow information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity or air indicates deceleration or idle.

The MAF sensor produces a frequency signal which can be monitored using a Tech 2. The frequency will vary within a range of around 4 to 7 g/s at idle to around 25 to 40 g/s at maximum engine load. DTC P0101 will be set if the signal from the MAF sensor does not match a predicted value based on throttle position and engine RPM.

Conditions for setting the DTC
- The engine is running.
- No TP sensor and MAP sensor DTCs are set.
- No MAF frequency DTCs are set.
- System voltage is between 11.5 volts and 16 volts.

Action Taken When the DTC Sets
- The PCM will illuminate the malfunction indicator lamp (MIL) the first time the fault is detected.
- The PCM calculates an air flow value based on idle air Control valve position, throttle position, RPM and barometric pressure.
- The PCM will store condition which were present when the DTC was set as Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC
- The PCM will turn the MIL "OFF" on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
- A history DTC P0101 will clear after 40 consecutive trip cycle during which the warm up cycles have occurred without a fault.
- DTC P0101 can be cleared using the Tech 2 "Clear Info" function or by disconnecting the PCM battery feed.

Diagnostic Aids
An intermittent may be caused by the following:
- Poor connections.
- Mis routed harness.
- Rubbed through wire insulation.
- Broken wire inside the insulation.
- he duct work at the MAF sensor for leaks.
- An engine vacuum leak.
- The PCV system for vacuum leaks.
- An incorrect PCV valve.
- The engine oil dip stick not fully seated.
- The engine oil fill cap loose or missing.

Check for the following conditions:
- Poor connection at PCM - Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness - Inspect the wiring harness for damage. If the harness appears to be OK, observe the Mass Air Flow (MAF) display on the Tech 2 while moving connectors and wiring harnesses related to the sensor.
- Plugged intake air duct or filter element
- A wide-open throttle acceleration from a stop should cause the mass air flow displayed on a Tech 2 to increase from about 3 - 6 g/s at idle to 100 g/s or greater at the time of the 1-2 shift. If not, check for a restriction.

A change in the display will indicate the location of the fault.

If DTC P0101 cannot be duplicated, the information included in the Failure Records data can be useful in determined vehicle mileage since the DTC was last set.

If it is determined that the DTC occurs intermittently, performing the DTC P001 Diagnostic Chart may isolate the cause of the fault.

Steps 1 - 2:

Steps 3 - 6:

Steps 7 - 10:

Test Description