P0140
DTC P0140 HO2S CIRCUIT NO ACTIVITY DETECTED (BANK 1 / SENSOR 2)Component Location:
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
If the change of the rear HO2S signals is less than 0.3V during driving condition and fuel-cut, the PCM determines that a fault exists and a DTC is stored.
DTC Detecting Condition:
Schematic Diagram:
Signal Waveform & Data:
MONITOR SCANTOOL DATA
1. Warm up the engine to normal operating temperature.
2. Connect Scantool then, Ignition "ON" & Engine "ON"
3. Monitor the voltage difference between driving condition and fuel cut condition from the signal waveform of HO2S(B1/S2) or HO2S monitoring test.
Specification Max Voltage - Min Voltage = More than 0.3 V
4. Is the signal waveform switching within specification?
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 looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "System Inspection" procedure.
SYSTEM INSPECTION
1. Check Air Leakage
1. Visually/physically inspect the air leakage in intake/exhaust system as following items.
A. If OK, go to "Check for air leakage in EVAP Purge control valve" as below.
B. If NG, repair as necessary and go to "Verification of Vehicle Repair" procedure.
- Vacuum hoses for splits, kinks and improper connections.
- Throttle body gasket.
- Gasket between intake manifold and cylinder head. Seats between intake manifold and fuel injectors.
- Exhaust system between HO2S and Three way catalyst for air leakage.
2. Check for air leakage in EVAP Purge control valve.
A. With engine idling disconnect hose from EVAP purge valve side of hose.
B. Check no vacuum at EVAP purge solenoid valve.
C. Is vacuum available at purge valve when EVAP purge valve is not in operating?
YES: Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Check for air leakage in Positive Crankcase Ventilation Valve(PCV)" as below.
3. Check for air leakage in Positive Crankcase Ventilation Valve(PCV).
A. Remove PCV valve from cylinder head cover by pulling ventilation hose.
B. With engine idling block PCV valve opening.
C. Confirm that vacuum is felt.
D. Remove PCV valve.
E. Blow through valve from port "A" and verify that air comes out of port "B"
F. Blow through valve from port "B" and verified that no air comes out of port "A"
G. Has a problem been found?
YES: Repair or replace as necessary and go to "Verification Vehicle Repair" procedure.
NO: Go to "Check Fuel Pressure" as below.
2. Fuel Pressure Test
NOTE:
1. Be cautious that Fuel is explosive and an empty fuel tank can still contain explosive gases. When working on fuel system make sure to supply adequate ventilation to the work area. Do not smoke, and keep sparks and open flames away
2. The fuel system remains under pressure when the engine is not running. Release fuel system pressure before disconnecting any fuel line to reduce the chance of personal injury or fire damage to vehicle components.
1. Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel as necessary.
2. Install the fuel pressure gauge to the fuel pressure gauge adaptor.
3. Apply battery voltage to the terminal for the pump drive and activate the fuel pump: then, with fuel pressure applied, check that there is no fuel leakage from the pressure gauge or connection part.
4. Disconnect the vacuum hose from the pressure regulator, and plug the hose end. Measure the fuel pressure at idle.
Specification: 320 - 340 kPa (3.26 - 3.47 kg/sq.cm, 46 - 49 psi)
5. Measure the fuel presure when the vacuum hose is connected to the pressure regulator.
Specification: Approx. 255 kPa (2.57 kg/sq.cm, 37 psi)
6. Are the measured fuel pressure within specifications?
YES: Go to "Check injector leakage" as below.
NO: Repair or replace according to the below table. And then, go to "Verification of Vehicle Repair"procedure.
3. Check Injector Leakage
1. Ignition "OFF" after checking the Fuel Pressure Test.
2. Stop the engine and check for a change in the fuel pressure gauge reading for 5 minutes.
3. Does fuel pressure drop after engine is stopped?
YES: Go to "Component Inspection" procedure.
NO: Repair or replace according to the below table. And then, go to "Verification of Vehicle Repair"procedure.
COMPONENT INSPECTION
1. Visual Inspection of HO2S
1. Visually/physically inspect following items:
- Inspect the rear HO2S for Contaminated, deteriorated or aged Rear HO2S.
- If contamination is evident on the HO2S, replace contaminated sensor.
2. Is the HO2S visually I physically O.K.?
YES: Go to "Check PCM" as below.
NO:
- Substitute with a known - good HO2S and check for proper operation.
- If the problem is corrected replace HO2S and go to "Verification of Vehicle Repair" procedure.
2. Check PCM
1. Ignition "OFF" & Engine "OFF"
2. Connect Scantool and Ignition "ON"
3. Select simulation function on scantool.
4. Simulate voltage at terminal 1 of HO(2) sensor signal connector.
5. Does the HO(2) sensor signal value changes according to simulation voltage?
YES: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Substitute with a known - good PCM and check for proper operation.
If the problem is corrected, replace PCM and 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. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness tests have been verified as "Complete".
5. Are any DTCs present?
YES: Go to the applicable troubleshooting procedure.
NO: System is performing to specification at this time.