P1235
DTC P1235: Mass Airflow Sensor PlausibilityTECHNICAL DESCRIPTION
Compare the actual measurement of volumetric efficiency by a mass airflow sensor signal with volumetric efficiency estimated from a throttle position sensor (main or sub) signal.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Not applicable
Sensor (The sensor below is determined to be normal)
- Not applicable
DTC SET CONDITIONS
Logic Flow Chart:
Check Conditions
- The plausibility error of the throttle position sensor (main) is detected.
- The plausibility error of the throttle position sensor (sub) is detected.
Judgment Criterion
- For 0.36 second, the difference between the volumetric efficiency estimated by the throttle position sensor (main) and the volumetric efficiency estimated by the throttle position sensor (sub) is 8.8 percent or less.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle Pattern 17. OBD-II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Mass airflow sensor system failed.
- Intake system vacuum leak.
- There is some trash around mass airflow sensor.
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the diagnostic trouble code other than P1235 set?
YES : Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
NO : Go to Step 2.
STEP 2. Using scan tool MB991958, check data list item 10: Mass Airflow Sensor.
1. Start the engine and run at idle.
2. Set scan tool MB991958 to the data reading mode for item 10, Mass Airflow Sensor.
3. 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 between 1,350 and 1,670 mV.
- When the engine is revved, the mass airflow rate should increase according to the increase in engine speed.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : Go to Step 3.
NO : Refer to, DTC P0101 - Mass Airflow Circuit Range/Performance Problem, DTC P0102 - Mass Airflow Circuit Low Input, DTC P0103 - Mass Airflow Circuit High Input.
STEP 3. Check for intake system vacuum leak.
Q: Are there any abnormalities?
YES : Repair it. Then go to Step 6.
NO : Go to Step 4.
STEP 4. Check for foreign matter being around the mass airflow sensor.
Q: Are there any foreign matter?
YES : Repair it. Then go to Step 6.
NO : Go to Step 5.
STEP 5. Check the trouble symptoms.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle Pattern 17. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P1235 set?
YES : Replace the ECM. When the ECM is replaced, register the ID code. Then go to Step 6.
NO : It can be assumed that this malfunction is intermittent.
STEP 6. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle Pattern 17. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P1235 set?
YES : Retry the troubleshooting.
NO : The inspection is complete.