DTC P0101. Chevrolet Epica 2005

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Engine 🢒 Engine Controls - 2.5L (LBK) 🢒 DTC P0101

Circuit Description

The MAF sensor measures the amount of air which passes through the sensor in a given amount of time. The engine control module (ECM) uses this information to determine the operating requirements of the engine in order to control the fuel delivery. The ECM calculates the engine fuel requirements by monitoring the current flow on the signal wire from the MAF sensor. When the volume of air entering the MAF sensor increases, the current flow sensed by the ECM from the MAF sensor also increases. When the airflow decreases, the current sensed by the ECM also decreases. The ECM compares the actual MAF sensor voltage signal to the predicted MAF value. This comparison will determine if the signal is stuck, or is too low or too high for a given operating condition. If the ECM detects that the actual MAF sensor voltage signal is not within a predetermined range of the calculated MAF value, DTC P0101 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0101 Mass Air Flow (MAF) Sensor Performance

Condition for Running the DTC

•	DTCs P0121, P0122, and P0123 are not set.

•	The engine speed is between 1,000-3,500 RPM.

•	The relative engine load is between 0.3-0.7.

•	The fuel system is in Closed Loop.

•	The engine load is stable.

Conditions for Setting the DTC

The ECM detects that the MAF sensor signal is not within a predetermined range of the calculated MAF value.

Action Taken When the DTC Sets

•	The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

•	The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

•	Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

•	Any un-metered air that enters the engine downstream of the MAF sensor may cause this DTC to set.

•	A short between the signal circuit of the MAF sensor and a voltage circuit will skew the MAF sensor higher than normal at idle and less than normal at higher air flows.

•	A malfunctioning MAF sensor can cause excessive engine emissions.

•	The MAF display should increase from 0.45-0.95 g/s at idle to 4.28 g/s or more at the 2-3 shift during a wide-open throttle (WOT) acceleration. If not, inspect for a restriction in the induction system or the exhaust system.

•	If the condition is intermittent, refer to Intermittent Conditions in Engine Controls.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

Any un-metered air entering the engine may cause this DTC to set. This step eliminates any conditions which can cause a DTC to set with a normally operating MAF sensor.

This step tests for high resistance in the ignition 1 voltage circuit of the MAF sensor. The voltage measure at the probe of the test lamp should be within a specified voltage of the battery voltage.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views

Did you perform the Diagnostic System Check - Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Start the engine.
Observe the Diagnostic Trouble Code (DTC) Information with a scan tool.

Did the scan tool display any other DTCs set?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

Observe the Freeze Frame/Failure Records for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC . You may also operate the vehicle within the conditions that you observed from the Freeze/Frame Failure Records.

Did the DTC fail this ignition?

Go to Step 4

Go to Diagnostic Aids

Idle the engine.
Observe the MAP sensor kPa parameter with a scan tool.

Is the MAP sensor kPa parameter less than the specified value?

27 kPa

Go to DTC P0107

Go to Step 5

Does the scan tool indicate that the MAP sensor kPa parameter is more than the specified value?

103 kPa

Go to DTC P0108

Go to Step 6

Turn ON the ignition, with the engine OFF.
Observe the MAP sensor kPa parameter with a scan tool.
Compare the MAP sensor kPa parameter to a known good vehicle.

Is the MAP sensor kPa parameter within the specified value of the known good vehicle?

3.0 kPa

Go to Step 7

Go to DTC P0106

Observe the MAP sensor voltage parameter with a scan tool.
Start the engine.

Did the MAP sensor voltage parameter change value after you started the engine?

Go to Step 8

Go to DTC P0106

Turn ON the ignition, with the engine OFF.
Observe the TP sensor voltage parameter with a scan tool.
Press the accelerator pedal from a closed throttle position, to a wide open throttle position.

Did the TP sensor voltage parameter go from above the specified value to below the specified value?

Above 4.0 V to below 1.0 V

Go to Step 9

Go to DTC P0121

Turn OFF the ignition.
Inspect for air leaks in the following components:

•	The air induction system.

•	The MAF sensor O-ring seal

Inspect for the following conditions:

•	An obstructed intake air duct or a dirty restricted air filter element

•	Any debris that is blocking the air sensing filaments of the MAF sensor

•	Contamination on the air sensing filaments of the MAF sensor

•	Water intrusion in the air induction system

•	A restricted exhaust system--Refer to Restricted Exhaust in Engine Exhaust

•	An engine vacuum leak

Did you find and correct the condition?

Go to Step 19

Go to Step 10

Turn ON the ignition, with the engine OFF.
Measure the battery voltage with a DMM.
Disconnect the harness connector of the MAF sensor.
Connect a test lamp between the ignition 1 voltage circuit of the MAF sensor and a good ground. Refer to Probing Electrical Connectors and Circuit Testing in Wiring Systems.
Connect the DMM to the probe of the test lamp and a good ground. Refer to Measuring Voltage Drop and Circuit Testing in Wiring Systems.
Compare the battery voltage to the ignition 1 voltage of the MAF sensor.

Is the voltage within 0.5 volts of the specified value?

B+

Go to Step 11

Go to Step 17

Important: This procedure is using the 5 volt reference circuit of the MAP sensor to test the signal circuit of the MAF sensor. If DTC P0107 is set, refer to DTC P0107 , before proceeding with this test.

Connect a 3-amp fused jumper wire between the 5 volt reference circuit of the MAP sensor and the signal circuit of the MAF sensor. Refer to Circuit Testing in Wiring Systems.
Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

4.98 V

Go to Step 13

Go to Step 12

Test the MAF sensor signal circuit for the following conditions:

•	High resistance

•	A short to ground

•	A short to the MAF sensor low reference circuit

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 16

Probe the low reference circuit of the MAF sensor with a test lamp connected to B+.

Does the test lamp illuminate?

Go to Step 15

Go to Step 14

Test the low reference circuit of the MAF sensor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 16

Test for shorted terminals and for an intermittent and for a poor connection at the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 18

Test for shorted terminals and for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 19

Repair the high resistance in the ignition voltage circuit of the MAF sensor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 20

Replace the MAF sensor.

Did you complete the replacement?

Go to Step 20

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

Go to Step 20

Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 21

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK