P0139
DTC P0139 HO2S CIRCUIT SLOW RESPONSE (BANK 1 / SENSOR 2)Component Location:
GENERAL DESCRIPTION
The rear heated oxygen sensor is mounted on the rear side of the Catalytic Converter (warm-up catalytic converter) or in the rear exhaust pipe, which detects the catalyst efficiency. The rear heated oxygen sensor (HO2S) produces a voltage between 0 V and 1 V. This rear heated oxygen sensor is used to estimate the oxygen storage capability. If a catalyst has good conversion properties, the oxygen fluctuations are smoothed by the oxygen storage capacity of the catalyst. If the conversion provided by the catalyst is low due to aging, poisoning or misfiring, then the oxygen fluctuations are similar to signals from the front oxygen sensor.
DTC DESCRIPTION
The PCM monitors rich-lean switching time of rear heated oxygen sensor (HO2S) after fuel cut-off to validate dynamic behavior of rear heated oxygen sensor (HO2S). After detection of fuel cut-off engine operating state, the PCM measures rich-lean switching time of the rear heated oxygen sensor (HO2S) signal and compares it to the predetermined limit value. DTC P0139 is set when the switching time is bigger than the limit value.
DTC Detecting Condition:
Schematic Diagram:
Signal Waveform:
MONITOR DTC STATUS
NOTE: If any misfire, Purge Solenoid Valve, Mass Air Flow Sensor or O2 Sensor heater codes are present, DO ALL REPAIRS associated with those codes before proceeding with this troubleshooting tree.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Press F4(DTAL) to select DTC information from the DTCs menu.
3. Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Read "DTC Status" parameter.
5. Is parameter displayed "History(Not Present) fault"?
NOTE:
1. History (Not Present) fault: DTC occurred but has been cleared.
2. Present fault: DTC is occurring at present time.
YES: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for loose or poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to next step as below.
VISUAL / PHYSICAL INSPECTION
1. Visually/physically inspect the following items:
1. Ensure that the HO2S is securely installed.
2. Check for corrosion on terminals
3. Check for terminal tension (at the HO2S and at the PCM)
4. Check for damaged wiring
5. Check the HO2S ground circuit for a good connection
2. Check front and rear HO2S for connections being reversed. If HO2S connections reversed, switch connections properly.
3. Was a problem found in any of the above areas?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Exhaust System Inspection" procedure.
EXHAUST SYSTEM INSPECTION
1. Check the exhaust system for an exhaust leak near the engine.
2. Was an exhaust leak found?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Air Leakage Inspection" procedure.
AIR LEAKAGE INSPECTION
1. Visually/physically inspect the following items:
1. Vacuum hoses for splits, kinks and improper connections.
2. Exhaust system between HO2S and Three way catalyst for air leakage
3. EVAP system for leakage
4. PCV hose for proper installation
2. Was a problem found in any of the above areas?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO: Go to "Fuel Pressure Inspection" procedure.
FUEL PRESSURE INSPECTION
1. Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel as necessary.
2. install a fuel pressure gage
3. Inspect fuel pressure with engine idling at normal operating temperature.
Test Condition Ignition "ON" & Engine "ON" & Vacuum hose disconnected at Idle
Specification : 250 - 350 kPa (2.50-3.50 kg/sq.cm, 36-50 psi)
4. Is the fuel pressure within the specified value?
YES: Go to "Fuel Injector Inspection" procedure as below.
NO: Repair as necessary refer to inspection note as below and go to "Verification of Vehicle Repair" procedure.
NOTE:
1. Check if fuel line pressure decreases when accelerating quickly
a. If it does, check fuel pump maximum pressure. If pressure is OK, check fuel line and filter for clogging.
2. If fuel pressure is lower than specification: Check for fuel line pressure while pinching fuel return hose.
a. If pressure quickly increases, check pressure regulator.
b. If pressure gradually increases, check for clogging between fuel pump and pressure regulate: If hose is not clogged, check fuel pump maximum pressure.
3. If fuel pressure is higher than specification: Is fuel line clogged?
a. If it is not, replace pressure regulate:
b. If ft is, replace it.
FUEL INJECTOR INSPECTION
1. Ignition "OFF"
2. Check the fuel injectors for clogging or any restrictions.
Specification : No clogging and restriction
3. Is the fuel injector OK?
YES: Go to "Component Inspection" procedure.
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Visually/physically inspect following items:
1. Ensure that the sensor is securely installed.
2. Check for corrosion on terminals.
3. Check for damaged wiring.
Repair as necessary and go to next step.
2. Warm up the engine to normal operating temperature and check that HO2S signal is active.
3. Connect Scantool and monitor the "O2 SNSR VOLT.(B1152)" parameter on the Scantool data list.
Test Condition Ignition "ON" & Engine "ON" & In idle("Closed Loop")condition.
Specification : Above 0.6 V
4. Is sensor data near the specified value?
YES: Check for poor connection between PCM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Check HO2S for contamination, deterioration, or damage. Substitute with a known-good HO2S and check for proper operation. If the problem is corrected, replace HO2S and then go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History(Not Present) fault"?
YES: System performing to specification at this time. Clear the DTC
NO: Go to the applicable troubleshooting procedure.