P0101

DTC P0101 Mass Air Flow (MAF) System Performance (1 Of 2):

DTC P0101 Mass Air Flow (MAF) System Performance (2 Of 2):

Mass Air Flow (MAF) System:

CIRCUIT DESCRIPTION

The Mass Air Flow (MAF) sensor measures the amount of air which passes through it in a given amount of time. The Engine Control Module (ECM) uses this information to determine the operating conditions of the engine to control fuel delivery. A large quantity of air movement indicates acceleration, while a small quantity indicates deceleration or idle. As the amount of air entering the sensor increases, then so does the sensor signal current to the ECM. As air flow decreases, then so does the signal current to the ECM. The MAF sensor is located between the air intake tube and the air cleaner in the LH front engine compartment.


CONDITIONS FOR RUNNING THE DTC

- Engine speed greater than 2000 RPM.

- Throttle Position (TP) sensor less than 200.


CONDITIONS FOR SETTING THE DTC


- Maximum flow rate - Minimum flow rate less than 0.1g/sec.

- Condition present for at least 20 seconds.


ACTION TAKEN WHEN THE DTC SETS

- The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.

- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.


CONDITIONS FOR CLEARING THE MIL/DTC


- The MIL will turn "OFF" after three consecutively passing cycles without a fault present.

- A History DTC will clear after 40 consecutive warm-up cycles without a fault.

- DTC(s) can be cleared by using a scan tool or by disconnecting the ECM battery feed.


DIAGNOSTIC AIDS


Check for the following conditions:


- Skewed or stuck TP sensor. A faulty TP sensor or TP sensor circuit can cause the ECM to incorrectly calculate the predicted mass air flow value. Observe Throttle Angle with the throttle closed. If the Throttle Angle reading is not 0 to 13%, check for the following conditions and repair as necessary:

- Throttle plate sticking or excessive deposits on throttle plate or throttle bore,

- TP sensor signal circuit shorted to voltage,

- Poor connection or high resistance in the TP sensor ground circuit.

- Poor connection at ECM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

- Misrouted harness. Inspect the MAF sensor harness to ensure that it is not routed too close to high voltage wires such as spark plug leads.

- Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving connectors and wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the fault.

- Plugged intake air duct or dirty air filter element. A wide-open throttle acceleration from a stop should cause the mass air flow displayed on a scan tool to increase from about 2 to 3.5 g/s at idle to 100 g/s or greater at the time of the 1-2 shift. If not, check for a restriction.

It DTC P0101 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.


If any wiring repairs need to be made, Refer to Repa1r Procedures in Diagrams.


TEST DESCRIPTION


Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Engine OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

3. This step verifies that the malfunction is present.

4. This step verifies that the ignition feed voltage and a good ground are available at the MAF sensor.

5. Verifies that the MAF signal circuit is within range.