Vehicles For California
DTC P2237: Linear Air-Fuel Ratio Sensor Positive Current Control Circuit/Open [Vehicles for California]
CIRCUIT OPERATION
The linear air-fuel ratio sensor and the ECM are connected by the following three lines to detect the air-fuel ratio.
- The line between the linear air-fuel ratio sensor (terminal No. 1) and the ECM (terminal No. 56) detects the air-fuel ratio.
- The auxiliary line between the linear air-fuel ratio sensor (terminal No. 4) and the ECM (terminal No. 38) detects the air-fuel ratio.
- The line between the linear air-fuel ratio sensor (terminal No. 5) and the ECM (terminal No. 39) connected to ground.
TECHNICAL DESCRIPTION
- The ECM effects air/fuel ratio feedback control in accordance with the signals from the linear air-fuel ratio sensor.
- If the linear air-fuel ratio sensor has deteriorated, corrections will be made by the heated oxygen sensor (rear).
DESCRIPTIONS OF MONITOR METHODS
- If the electrical currents of the ECM line are not detected although being supplied by the ECM, the DTC is stored as an open circuit.
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)
- Linear air-fuel ratio sensor heater monitor
- Misfire monitor
- Fuel system monitor
Sensor (The sensor below is determined to be normal)
- Mass airflow sensor
- Engine coolant temperature sensor
- Intake air temperature sensor
- Barometric pressure sensor
- Throttle position sensor
- Accelerator pedal position sensor
DTC SET CONDITIONS
Check Conditions
- Battery positive voltage is between 10 and 16.5 volts.
- More than 220 seconds have passed since the engine starting sequence was completed.
Judgement Criteria
- The negative circuit voltage subtracted from the pumping circuit voltage is be lower than -2.1 volts or higher than 2.3 volts for 2 seconds.
- The pumping current is 0 milli ampere for 2 seconds.
FAIL-SAFE AND BACKUP FUNCTION
- Does not control air-fuel ratio closed loop.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnosis Function - OBD-II Drive Cycle - Pattern 22. OBD- II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Linear air-fuel ratio sensor failed.
- Open linear air-fuel ratio sensor circuit, or connector damage.
- 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. Check harness connector B-21 at linear air-fuel ratio sensor and harness connector B-108 at ECM for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 2.
NO : Repair or replace it. Then go to Step 5.
STEP 2. Check for open circuit between linear air-fuel ratio sensor connector B-21 (terminal No. 1) and ECM connector B-108 (terminal No. 56).
Q: Is the harness wire in good condition?
YES : Go to Step 3.
NO : Repair it. Then go to Step 5.
STEP 3. Test the OBD-II drive cycle.
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 and delete the DTC.
3. Carry out the test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22. OBD- II Drive Cycle
4. Check the diagnostic trouble code (DTC).
Q: Is DTC P2237 set?
YES : Then go to Step 4.
NO : It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions. Troubleshooting Contents
STEP 4. Replace the linear air-fuel ratio sensor.
1. Replace the linear air-fuel ratio sensor.
2. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22. OBD- II Drive Cycle
3. Check the diagnostic trouble code (DTC).
Q: Is DTC P2237 set?
YES : Replace the ECM. Then go to Step 5.
NO : The inspection is complete.
STEP 5. 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 22. OBD- II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P2237 set?
YES : Retry the troubleshooting.
NO : The inspection is complete.