P0101

DTC P0101: Volume Air Flow Circuit Range/Performance Problem

Volume Air Flow Sensor Circuit Part 1:

Volume Air Flow Sensor Circuit Part 2:

CIRCUIT OPERATION
- The volume air flow sensor power is supplied from the MFI relay (terminal No. 4), and the ground is provided on the ECM (terminal No. 40) or PCM (terminal No. 16) .
- 5-volt power is applied to the volume air flow sensor output terminal (terminal No. 3) from the ECM (terminal No. 90) or PCM (terminal No. 65) . The volume air flow sensor generates a pulse signal when the output terminal and ground are opened/closed (opened/short).

TECHNICAL DESCRIPTION
- While the engine is running, the volume air flow sensor outputs a pulse signal which corresponds to the volume of air flow.
- The ECM or PCM checks whether the frequency of this signal output by the volume air flow sensor while the engine is running is at or above the set value.
- When the throttle position sensor output voltage is low, the ECM or PCM causes the power transistor to be "ON" to send an air flow sensor reset signal to the air flow sensor. In response to the reset signal, the air flow sensor resets the filter circuit and improves the ability of the air flow sensor to measure the amount of air in a small air intake region.

DTC SET CONDITIONS

Check Conditions
- Throttle position sensor output voltage is 1.5 volts or higher.
- Engine speed is higher than 2,000 r/min.

Judgement Criteria
- Volume air flow sensor output frequency has continued to be 60 Hz or lower for 2 seconds.

Check Conditions
- Throttle position sensor output voltage is 2 volts or lower.
- Engine speed is lower than 2,000 r/min.

Judgement Criteria
- Volume air flow sensor output frequency has continued to be 800 Hz or higher for 2 seconds.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Volume air flow sensor failed.
- Open or shorted volume air flow sensor circuit, or loose connector.
- ECM failed.
- PCM failed.
- Air leak between volume air flow sensor and throttle body.

DIAGNOSIS

Required Special Tool:
- MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, check data list item 12: Volume Air Flow Sensor.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to the data reading mode for item 12, Volume Air Flow Sensor.
4. Warm up the engine to normal operating temperature: 80 °C to 95 °C (176 °F to 203 °F).
- The standard value during idling should be 10 Hz or more.
- When the engine is revved, the frequency should increase according to the increase in engine speed.

5. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the sensor operating properly?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.

NO: Go to Step 2.

STEP 2. Measure the reset signal voltage at volume air flow sensor connector B-105 by backprobing.

1. Do not disconnect connector B-105.
2. Turn the ignition switch to the "ON" position.

3. Measure the voltage between terminal No. 7 and ground by backprobing.
- Voltage should measure between 6.0 and 9.0 volts.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage between 6.0 and 9.0 volts?

YES: Go to Step 5.

NO: Go to Step 3.

STEP 3. Check connector B-105 at volume airflow sensor and connector C-121 at ECM or connector C-120 at PCM for damage.

Q: Is the connector in good condition?

YES: Go to Step 4.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 9.

STEP 4. Check for short circuit to ground between volume air flow sensor connector B-105 (terminal No. 7) and ECM connector C-121 (terminal No. 19) or PCM connector C-120 (terminal No. 19) .

Q: Is the harness wire in good condition?

YES: Replace the volume air flow sensor. Then go to Step 9.

NO: Repair it. Then go to Step 9.

STEP 5. Measure the reset signal voltage at volume air flow sensor connector B-105 by backprobing.

1. Do not disconnect connector B-105.
2. Start the engine and run at idle.

3. Measure the voltage between terminal No. 7 and ground by backprobing.
- When the engine idling, voltage should measure 1.0 volt or less.
- When the engine speed is 3,000 r/min, voltage should measure between 6.0 and 9.0 volts.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage within the specified range?

YES: Go to Step 8.

NO: Go to Step 6.

STEP 6. Check connector B-105 at volume airflow sensor and connector C-121 at ECM or connector C-120 at PCM for damage.

Q: Is the connector in good condition?

YES: Go to Step 7.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 9.

STEP 7. Check for open circuit and harness damage between volume air flow sensor connector B-105 (terminal No. 7) and ECM connector C-121 (terminal No. 19) or PCM connector C-120 (terminal No. 19) .

Q: Is the harness wire in good condition?

YES: Replace the ECM or PCM. Then go to Step 9.

NO: Repair it. Then go to Step 9.

STEP 8. Replace the volume airflow sensor.
1. Replace the volume air flow sensor.
2. Carry out a test drive with the drive cycle pattern. Refer to Trouble Code Diagnosis- OBD-II Drive Cycle - Procedure 6 - Other Monitor.
3. Check the diagnostic trouble code (DTC).

Q: Is DTC P0101 set?

YES: Replace the ECM or PCM. Then go to Step 9.

NO: The procedure is complete.

STEP 9. Perform the OBD-11 drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to, Procedure 6 - Other Monitor.
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0101 set?

YES: Repeat the troubleshooting.

NO: The procedure is complete.