Mass Air Flow (MAF) Circuit Low Input

Description:

How does a P0102 code trigger the check engine light? The engine light will come on if the following concern is present:

The Mass Air Flow Sensor circuit is monitored by the powertrain control module (computer), for low voltage (which translates to low air flow) through the Comprehensive Component Monitor (CCM). With the key on and engine running, if the voltage drops below a minimum value this code will be set, causing the check engine light to illuminate.

Possible Causes:

MAF Sensor disconnected
MAF Sensor circuit open to computer
Vehicle Power circuit open to MAF Sensor
Power Ground circuit open to MAF Sensor
MAF Sensor Return circuit open to PCM
MAF Sensor circuit shorted to Ground
Intake air leak near MAF Sensor
Damaged MAF Sensor
Damaged computer

Diagnostic Help:

Refer to an appropriate manual for specification. If MAF Sensor voltage reading is below minimum limit with key on engine running then concern is a hard fault (present now). If all values are in spec proceed with intermittent diagnosis (refer to our “Intermittent Diagnosis Help” article through the “articles” link on the Navigation Bar). You may also use the “Get Help” link if you need specifications or have any other related questions.

Intake Cam Position Timing Over Retarded – Bank 2

Description:

How does a P0022 code trigger the check engine light? This code will trigger the check engine light under the following condition:

The comprehensive component monitor, referred to as the CCM, monitors the Variable Camshaft Timing (VCT) position for over-retarded cam timing. If the cam timing exceeds a maximum calibrated limit or is stuck in a retarded position, the check engine light will come on and set this trouble code.

Possible Causes:

Incorrect camshaft timing
VCT solenoid valve stuck open or continuous oil flow to piston chamber
Camshaft advance mechanism binding, or faulty VCT unit

Diagnostic Help:

This check engine light code is caused by a mechanical fault of the VCT unit or related components, so there is no need for electrical diagnosis. Possible symptoms may include rough idle, stall or hard start. Refer to manufacturer specific component tests for the VCT unit. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instructions.

Intake Cam Position Timing Over Advanced – Bank 2

Description:

How does a P0021 code trigger the check engine light? This code will trigger the check engine light under the following condition:

The comprehensive component monitor, referred to as the CCM, monitors the Variable Camshaft Timing (VCT) position for over-advanced cam timing. If the cam timing exceeds a maximum calibrated limit or is stuck in an advanced position, the check engine light will come on and set this trouble code.

Possible Causes:

Incorrect camshaft timing
VCT solenoid valve stuck open or continuous oil flow to piston chamber
Camshaft advance mechanism binding, or faulty VCT unit

Diagnostic Help:

This check engine light code is caused by a mechanical fault of the VCT unit or related components, so there is no need for electrical diagnosis. Possible symptoms may include rough idle, stall or hard start. Refer to manufacturer specific component tests for the VCT unit. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instructions.

Intake Cam Position Actuator Open Circuit – Bank 2

Description:

How does a P0020 code trigger the check engine light? This code will trigger the check engine light under the following condition:

The comprehensive component monitor, referred to as the CCM, monitors the Variable Camshaft Timing (VCT) circuit to the computer for high and low voltages. If the voltage falls below a set limit for a specific amount of time during this test, the check engine light will come on and set this trouble code.

Possible Causes:

Open or short in the VCT circuit
Open in the Vehicle Power circuit
Open or short in the VCT solenoid valve itself
Damaged computer (PCM)

Diagnostic Help:

This check engine light code is caused by a circuit fault of the VCT system. Testing should include all related wiring circuits, the VCT solenoid and PCM itself. Please refer to out article on Automotive Circuit Testing for help with this. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instructions.

Variable Camshaft Timing Over Retarded – Bank 1

Description:

How does a P0012 code trigger the check engine light? This code will trigger the check engine light under the following condition:

The comprehensive component monitor, referred to as the CCM, monitors the Variable Camshaft Timing (VCT) position for over-retarded cam timing. If the cam timing exceeds a maximum calibrated limit or is stuck in a retarded position, the check engine light will come on and set this trouble code.

Possible Causes:

Incorrect camshaft timing
VCT solenoid valve stuck open or continuous oil flow to piston chamber
Camshaft advance mechanism binding, or faulty VCT unit

Diagnostic Help:

This check engine light code is caused by a mechanical fault of the VCT unit or related components, so there is no need for electrical diagnosis. Possible symptoms may include rough idle, stall or hard start. Refer to manufacturer specific component tests for the VCT unit. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instructions.

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