[ Model - ECLIPSE CROSS / Year - 2018 ]
2018 / ECLIPSE CROSS / EC - Workshop Manual
13 -FUEL > 13A-DIRECT INJECTION AND MULTIPOINT FUEL INJECTION (DI AND MPI) > TROUBLESHOOTING > DIAGNOSIS CODE PROCEDURES > CODE NO. P0031 LINEAR A/F SENSOR HEATER CIRCUIT LOW INPUT
Code No. P0031: Linear A/F Sensor Heater Circuit Low Input
 
 
 
 
OPERATION
  • Power is supplied to the heater power terminal of the linear A/F sensor connector from the engine control relay.
  • The heater of the linear A/F sensor connector is controlled by the power transistor in the engine-ECU connector terminal LHFL.
 
 
FUNCTION
  • The engine-ECU checks whether the heater current is within a specified range when the heater is on.
  • The engine-ECU checks whether the heater voltage is within a specified range when the heater is off.
 
 
TROUBLE JUDGEMENT
Check Conditions
  • More than 2 seconds have passed since the engine starting sequence was completed.
  • While the linear A/F sensor heater is on.
  • Battery positive voltage is more than 11 V and is less than 16.5 V.
Judgement Criterion
  • The linear A/F sensor heater current is less than 0.17 A for 2 seconds.
Check Conditions
  • More than 2 seconds have passed since the engine starting sequence was completed.
  • While the linear A/F sensor heater is off.
  • Battery positive voltage is more than 11 V and is less than 16.5 V.
Judgement Criterion
  • The linear A/F sensor heater voltage is less than 2.0 V for 2 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
PROBABLE CAUSES
  • Failed linear A/F sensor heater
  • Open/short circuit or harness damage in linear A/F sensor heater circuit or loose connector contact
  • Failed engine-ECU
 
 
DIAGNOSIS PROCEDURE
STEP 1. Check linear A/F sensor itself.
  • Linear A/F sensor check (Refer to ).
Is the check result normal?
Go to Step 2.
Replace the linear A/F sensor.
 
STEP 2. Perform voltage measurement at linear A/F sensor connector.
  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal power supply line and body earth.
OK: System voltage
Is the check result normal?
Go to Step 3.
Repair the connector(s), or check and repair of short to earth, and open circuit in power supply line between linear A/F sensor connector and engine control relay connector.
 
STEP 3. Perform voltage measurement at engine-ECU connector.
  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal LHFL and body earth.
OK: System voltage
Is the check result normal?
Go to Step 4.
Repair the connector(s), or check and repair of short circuit to earth, and open circuit in LHFL line between linear A/F sensor connector and engine-ECU connector.
 
STEP 4. Check of damage in power supply line between linear A/F sensor connector and engine control relay connector.
Is the check result normal?
Go to Step 5.
Repair the connector(s) or wiring harness.
 
STEP 5. Check of damage in LHFL line between linear A/F sensor connector and engine-ECU connector.
Is the check result normal?
Go to Step 6.
Repair the connector(s) or wiring harness.
 
STEP 6. M.U.T.-IIISE diagnosis code
  • Reconfirmation of diagnosis code.
Is the diagnosis code set?
Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).