[ 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. P0037 OXYGEN SENSOR (REAR) HEATER CIRCUIT LOW INPUT
Code No. P0037: Oxygen Sensor (rear) Heater Circuit Low Input
 
 
 
 
OPERATION
  • Power is supplied to the heater power terminal of the oxygen sensor (rear) connector from the engine control relay.
  • The heater of the oxygen sensor (rear) connector is controlled by the power transistor in the engine-ECU connector terminal OHRL.
 
 
FUNCTION
  • The power supply to the oxygen sensor (rear) heater is controlled by the ON/OFF control of the power transistor in the engine-ECU.
  • Heating the oxygen sensor (rear) heater enables the oxygen sensor (rear) to provide good response even when the exhaust emission temperature is low.
 
 
TROUBLE JUDGEMENT
Check Conditions
  • More than 2 seconds have passed since the engine starting sequence was completed.
  • While the oxygen sensor (rear) heater is on.
  • Battery positive voltage is more than 11 V and is less than 16.5 V.
Judgement Criterion
  • The oxygen sensor (rear) 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 oxygen sensor (rear) heater is off.
  • Battery positive voltage is more than 11 V and is less than 16.5 V.
Judgement Criterion
  • The oxygen sensor (rear) heater voltage is less than 2.0 V for 2 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
PROBABLE CAUSES
  • Failed oxygen sensor (rear) heater
  • Open/short circuit or harness damage in oxygen sensor (rear) heater circuit or loose connector contact
  • Failed engine-ECU
 
 
DIAGNOSIS PROCEDURE
STEP 1. Perform resistance measurement at oxygen sensor (rear) connector.
  • Disconnect connector, and measure at sensor side.
  • Resistance between terminal heater power supply line and engine-ECU OHRL line.
OK: 4.5 - 8.0 Ω (at 20°C)
Is the check result normal?
Go to Step 2.
Replace the oxygen sensor (rear).
 
STEP 2. Perform voltage measurement at oxygen sensor (rear) connector.
  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal heater 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 oxygen sensor (rear) 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 OHRL 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 to earth, and open circuit in OHRL line between oxygen sensor (rear) connector and engine-ECU connector.
 
STEP 4. Check of damage in OHRL line between oxygen sensor (rear) connector and engine-ECU connector.
Is the check result normal?
Go to Step 5.
Repair the connector(s) or wiring harness.
 
STEP 5. Check of damage in power supply line between oxygen sensor (rear) connector and engine control relay 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 ).