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HOMESERVICE MANUALSMAZDA2006B4000 BASE, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE SYMPTOM TROUBLESHOOTING - (3 OF 5)DTC APPLICATION CHART - POWERTRAIN CONTROL MODULE (PCM)HEATED OXYGEN SENSOR (HO2S) NOT SWITCHING - UPSTREAM
2006 Mazda B4000 Base, Automatic

Heated Oxygen Sensor (Ho2S) Not Switching - Upstream

2006 Mazda B4000 Base, AutomaticSECTION Heated Oxygen Sensor (Ho2S) Not Switching - Upstream
DTC P1131, P1151 DETECTION CONDITION & POSSIBLE CAUSES

DTC P1131, P1151 HEATED OXYGEN SENSOR (HO2S) UPSTREAM NOT SWITCHING
DETECTION CONDITION 
  • P1131 (Bank 1) and P1151 (Bank 2) indicate HO2S is indicating lean at the end of a test trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects a switch for a calibrated amount of time.
POSSIBLE CAUSE 
  • Fuel system:
    • Excessive fuel pressure
    • Leaking fuel injector(s)
    • Leaking fuel pressure regulator
    • Low fuel pressure or running out of fuel
    • Contaminated fuel injector(s)
  • Induction system:
    • Air leaks after the mas air flow (MAF)
    • Vacuum leaks (vacuum lines and gaskets)
    • Positive ceankcase ventilation (PCV) system.
    • Improperly seated engine oil dipstick.
  • Exhaust gas recirculation (EGR) system:
    • Leaking gasket
    • Stuck open EGR valve
  • Base engine:
    • Oil overfill
    • Cam timing
    • Cylinder compression
    • Exhaust leaks before or near HO2S(s)
  • Electrical:
    • Short to VPWR in harness or HO2S
    • Water in harness connector
    • Open/shorted HO2S
    • Damaged HO2S
    • Damaged powertrain control module (PCM)
HINT  HO2S Description 
  • Detects the presence of oxygen in the exhaust and produces a variable voltage (0.0-1.1 V) according to the amount of oxygen detected.
    • A high concentration of oxygen (lean air/fuel ratio) in the exhaust produces a low voltage signal (less than 0.4 V).
    • A low concentration of oxygen (rich air/fuel ratio) in the exhaust produces a high voltage signal (greater than 0.6 V).
  • Provides feedback to the PCM indicating air/fuel ratio in order to achieve a near stoichiometric air/fuel ratio of 14.7:1 during closed loop engine operation.
G04306968Courtesy of MAZDA MOTORS CORP.
G04306969Courtesy of MAZDA MOTORS CORP.
G04306970Courtesy of MAZDA MOTORS CORP.
G04306971Courtesy of MAZDA MOTORS CORP.
G04306972Courtesy of MAZDA MOTORS CORP.
DTC P1131, P1151 DIAGNOSTIC PROCEDURE

DTC P1131, P1151 HEATED OXYGEN SENSOR (HO2S) UPSTREAM NOT SWITCHING
STEP INSPECTION ACTION
1
  • Was the PCM quick test performed?
 Yes Go to next step.
No Perform PCM quick test. See PCM QUICK TEST  .
2 DTCS P1131, P1151: UPSTREAM HO2S(S) NOT SWITCHING
  • Check air intake system for leaks and damage.
  • Verify integrity of PCV system.
  • Check for vacuum leaks.
  • Are any of the above concerns present? 
 Yes Repair as necessary. Go to step 21.
No Go to next step.
3 PERFORM KOER SELF-TEST
  • Disconnect fuel vapor hose from intake manifold and plug fitting at intake manifold.
  • Start engine and run at 2, 000 rpm for 5 minutes and return to idle.
  • Perform KOER self-test.
  • Is DTC P1131 and/or P1151 present? 
 Yes Go to next step.
No Perform EVAP LEAK TEST to locate EVAP system leak.
See EVAPORATIVE EMISSION SYSTEM LEAK TEST .
4 HO2S CIRCUIT TEST (WITH LEAN DTCS)
  • Key OFF.
  • Disconnect suspect HO2S related to the DTC.
    • P1131 =HO2S11 (front RH)
    • P1151 =HO2S21 (front LH)
  • Key on, engine off (KOEO).
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Access O2S11 (front RH) or O2S21 (front LH) PID.
    NOTE:
    • If a spark occurs, indicating a short, remove jumper and check for short to ground (check fuse in heater circuit).
  • Jumper HO2S SIG to HO2S VPWR at the HO2S vehicle harness connector.
  • Is the reading 1.30 V or greater? 
 Yes Go to next step.
No An open or short to ground exists in the vehicle harness or PCM. Go to step 7.
5 CHECK SIGNAL RETURN CIRCUIT FOR SHORTS AND OPENS
  • Measure resistance of HO2S SIG RTN circuit between the HO2S vehicle, harness connector and the battery ground terminal.
  • Is the resistance reading less than 5.0 ohms? 
 Yes Connect all components. Go to step 10.
No Check wiring for open or short to ground. Go to next step.
6 CHECK HO2S SIGNAL RETURN CIRCUIT IN VEHICLE HARNESS
  • Disconnect PCM.
  • Install breakout box, leave PCM disconnected.
  • Measure resistance of the HO2S SIG RTN circuit between PCM test pin 91 and the HO2S vehicle harness connector.
  • Is resistance reading less than 5.Q ohms? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Go to step 21.
No Repair open circuit. Go to step 21.
7 CHECK RESISTANCE OF HO2S GROUND CIRCUITS
  • Disconnect PCM.
  • Install breakout box, leave PCM disconnected.
  • Measure resistance of HO2S SIG circuit between PCM test pin and the HO2S vehicle harness connector. Use the following pin assignment and record the reading:
    • HO2S-11 SIG = Test Pin 60
    • HO2S-21 SIG = Test Pin 87
    • Is the resistance reading less than 5.0 ohms? 
 Yes Go to next step.
No Repair open circuit. Go to step 21.
8 CHECK HO2S CIRCUIT WIRING HARNESS FOR SHORT TO GROUND
  • Measure resistance of HO2S SIG circuit between PCM test pin 60 or 87 and PCM test pin 103 (PWR GND).
  • Measure resistance of HO2S SIG circuit between PCM test pin 60 or 87 and PCM test pin 91 (SIG RTN).
  • Is each resistance greater than 10K ohms? 
 Yes Go to next step.
No Repair short circuit. Go to step 21.
9 CHECK HO2S FOR SHORT TO GROUND
  • Connect HO2S.
  • Measure resistance of HO2S SIG circuit between PCM test pin 60 or 87 and PCM test pin 103 (PWR GND).
  • Measure resistance of HO2S SIG circuit between PCM test pin 60 or 87 and PCM test pin 91 (SIG RTN).
  • Is resistance greater than 10K ohms? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Go to step 21.
No Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION . Go to step 21.
10 CHECK HO2S ABILITY TO GENERATE A VOLTAGE GREATER THAN 0.5 VOLT
  • Inspect HO2S harness for chafing, burned wiring or other damage and repair as necessary.
  • Disconnect the suspect HO2S from vehicle harness.
  • Connect multimeter to HO2S signal and HO2S SIG RTN or HO2S GND at the HO2S connector.
  • Run engine at 2, 000 rpm for three minutes.
  • Run KOER self-test and monitor HO2S voltage.

    See ON - BOARD DIAGNOSTIC TESTS .

  • Key OFF.
  • Is voltage greater than 0.5 V during or at the end of self-test? 
 Yes Go to next step.
No Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION . Go to step 21.
11 MONITOR HO2S (PID) FOR PROPER SWITCHING
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Access O2S11 (front RH) or O2S21 (front LH) PID while wiggling, bending and shaking small sections of the engine harness from the HO2S to the PCM.
  • Key OFF.
  • Does the HO2S voltage stay high (greater than 0.45 volt) or low (less than 0.45 volt)? 
 Yes Isolate cause of lack of HO2S switching and repair as necessary. Go to step 21.
No Go to next step.
12 CHECK FUEL PRESSURE
WARNING:
  • The fuel system is pressurized when the engine is not running. To prevent injury or fire, use caution when working on the fuel system.
  • Install fuel pressure gauge.
  • Key on, engine off (KOEO).
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select Active Command Modes.
  • Access output test mode and run the fuel pump to obtain maximum fuel pressure.
    NOTE:
    • The fuel pump will only operate for approximately 8 seconds when output test mode is selected and activated.
  • Is the fuel pressure 207-448 kPa (30-65 psi) for 3.0L / 4.0L or 240-380 kPa (35-55 psi) for 2.3L? 
 Yes Fuel system is capable of required fuel pressure. Go to next step.
No See GENERAL PINPOINT TEST 5: FUEL DELIVERY SYSTEM .
13 CHECK INJECTOR FAULT PIDS
  • Access INJ1F through INJ6F PIDs.
  • Is an injector(s) fault present? 
 Yes Go to next step.
No Go to step 17.
14 CHECK FUEL INJECTOR(S) AND HARNESS RESISTANCE
NOTE:
  • This erases continuous memory DTCs.
  • Disconnect PCM.
  • Install breakout box, leave PCM disconnected.
    NOTE:
    • Use the injector fault PID to determine the fuel injector circuit(s) requiring testing.
  • Measure resistance of suspect fuel injector between suspect INJ circuit and PCM test pin 71 (VPWR).
  • Is the resistance between 11.0-18.0 ohms for 4.0L or 8.5-15.5 ohms for 3.0L or 11.0-13.0 ohms for 2.3L? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Go to step 21.
No Go to next step.
15 CHECK FUEL INJECTOR HARNESS RESISTANCE
  • Disconnect fuel injector harness connector at the suspect fuel injector.
  • Measure resistance of VPWR circuit between PCM test pin 71 (VPWR) and the fuel injector harness connector.
  • Measure resistance of INJ circuit between suspect INJ circuit PCM test pin and the fuel injector harness connector.
  • Is each resistance less than 5.0 ohms? 
 Yes Go to next step.
No Repair open harness circuit. Go to step 21.
16 CHECK FUEL INJECTOR HARNESS CIRCUIT FOR SHORT TO POWER AND GROUND
  • Measure resistance between INJ at suspect fuel injector and PCM test pin 71 or 97 (VPWR).
  • Measure resistance between INJ at suspect fuel injector and PCM test pin 51 or 103(PWR GND).
  • Is each resistance greater than 10K ohms? 
 Yes Go to next step.
No Repair short circuit. Go to step 21.
17 FLOW TEST FUEL INJECTOR(S)
  • Use a fuel injector tester to flow test the fuel injectors according to the instructions for the tester.
    • Flow rate specification is 5.5 kg/hr (12 lb/hr) for 3.0L or 8.7 kg/hr (19 lb/hr) for 4.0L, 9.6 kg/hr (21 lb/hr) for 2.3L?
    • Are the leakage and flow within specification? 
 Yes Go to next step.
No Replace the fuel injector(s). See FUEL INJECTION SUPPLY MANIFOLD AND FUEL INJECTOR - 2.3L REMOVAL / INSTALLATIONFUEL INJECTION SUPPLY MANIFOLD AND FUEL INJECTOR - 3.0L REMOVAL / INSTALLATION or FUEL INJECTION SUPPLY MANIFOLD AND FUEL INJECTOR - 4.0L REMOVAL / INSTALLATION . Go to step 21.
18 INSPECT INDUCTION SYSTEM FOR AIR LEAKS
  • Inspect the following areas for signs of air leaks:
    • Inlet tube(s) from air cleaner to throttle body
    • Gaskets which seal upper and lower intake manifold
    • Vacuum hoses and lines for cracks and proper connections
    • PCV system
  • Are their any signs of leaks or damage? 
 Yes Repair as necessary. Go to step 21.
No Go to next step.
19 CHECK CYLINDER COMPRESSION
  • Check cylinder compression. See ENGINE COMPONENT TEST .
    NOTE:
    • Use misfire DTCs (if present) to determine which cylinder's compression to check. Otherwise check all cylinders.
  • Are cylinder compression readings within specification? 
 Yes Go to next step.
No Repair as necessary. Go to step 21.
20 TEST DRIVE WHILE MONITORING HO2S PID FOR PROPER SWITCHING
NOTE:
  • This step requires an observer to monitor PID for proper operation.
  • Access O2S11 (Front RH) or O2S21 (Front LH) HO2S PID.
  • While observer views PID, test drive vehicle under different road conditions in an attempt to simulate the original fault.
  • Does HO2S appear to switch properly? 
 Yes Unable to duplicate fault. Go to next step.
No Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION . Go to next step.
21 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Connect all disconnected connectors.
  • Clear DTCs from PCM memory using the WDS or equivalent tester generic OBD-II function.
  • Perform PCM quick test.
  • Is same DTC present? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Repeat PCM quick test.
No If any other DTC is present, Go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) . If no DTC is present, troubleshooting is complete.


DTC P1132, P1152 DETECTION CONDITION & POSSIBLE CAUSES

DTC P1132, P1152 HEATED OXYGEN SENSOR (HO2S) UPSTREAM NOT SWITCHING
DETECTION CONDITION 
  • P1132 (Bank 1) and P1152 (Bank 2) indicate HO2S is indicating rich at the end of a test trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects a switch for a calibrated amount of time.
POSSIBLE CAUSE 
  • Fuel system:
    • Excessive fuel pressure
    • Leaking fuel injector(s)
    • Leaking fuel pressure regulator
    • Low fuel pressure or running out of fuel
    • Contaminated fuel injector(s)
  • Induction system:
    • Air leaks after the mas air flow (MAF) sensor
    • Vacuum leaks (vacuum lines and gaskets)
    • Positive crankcase ventilation (PCV) system
    • Improperly seated engine oil dipstick.
  • Exhaust gas recirculation (EGR) system:
    • Leaking gasket
    • Stuck open EGR valve
  • Base engine:
    • Oil overfill
    • Cam timing
    • Cylinder compression
    • Exhaust leaks before or near HO2S(s)
  • Electrical:
    • Short to VPWR in harness or HO2S
    • Water in harness connector.
    • Open/shorted HO2S
    • Damaged HO2S
    • Damaged powertrain control module (PCM)
HINT  HO2S Description 
  • Detects the presence of oxygen in the exhaust and produces a variable voltage (0.0-1.1 V) according to the amount of oxygen detected.
    • A high concentration of oxygen (lean air/fuel ratio) in the exhaust produces a low voltage signal (less than 0.4 V).
    • A low concentration of oxygen (rich air/fuel ratio) in the exhaust produces a high voltage signal (greater than 0.6 V).
  • Provides feedback to the PCM indicating air/fuel ratio in order to achieve a near stoichiometric air/fuel ratio of 14.7:1 during closed loop engine operation.
G04306973Courtesy of MAZDA MOTORS CORP.
G04306974Courtesy of MAZDA MOTORS CORP.
G04306975Courtesy of MAZDA MOTORS CORP.
G04306976Courtesy of MAZDA MOTORS CORP.
G04306977Courtesy of MAZDA MOTORS CORP.
DTC P1132, P1152 DIAGNOSTIC PROCEDURE

DTC P1132, P1152 HEATED OXYGEN SENSOR (HO2S) UPSTREAM NOT SWITCHING
STEP INSPECTION ACTION
1
  • Was the PCM quick test performed?
 Yes Go to next step.
No Perform PCM quick test. See PCM QUICK TEST  .
2 DTCS P1132 AND P1152: UPSTREAM HO2S(S) NOT SWITCHING
  • Check air intake system for obstructions or damage.
  • Check air cleaner element, air cleaner housing for blockage.
  • Check PCV system for proper hose routing.
  • Are any of these concerns present? 
 Yes Repair as necessary.
Go to step 17.
No Go to next step.
3 PERFORM KOER SELF-TEST
  • Disconnect fuel vapor hose from intake manifold and plug fitting at intake manifold.
  • Start engine and run at 2, 000 rpm for 5 minutes and return to idle.
  • Perform key on, engine running (KOER) self-test.
  • Is DTC P1132 and/or P1152 present? 
 Yes Go to next step.
No Purge solenoid may be stuck open.
Go to EVAP Leak Test.
See EVAPORATIVE EMISSION SYSTEM LEAK TEST .
4 HO2S CIRCUIT CHECK (WITH RICH DTCS)
  • Key OFF.
  • Disconnect the HO2S related to the DTC.
    • P1132 = HO2S11 (Front RH)
    • P1152 = HO2S21 (Front LH)
  • Key ON, Engine Running (KOER).
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Access O2S11 (Front RH) or O2S21 (Front LH) PID.
  • Is the reading 0.2 V or less? 
 Yes Go to step 6.
No A short to power exists.
Go to next step.
5 CHECK FOR SHORTS TO VOLTAGE SOURCE IN THE HARNESS CIRCUIT
  • Key OFF.
  • Disconnect WDS or equivalent tester.
  • Disconnect PCM.
  • Install breakout box, leave PCM disconnected.
  • For DTC P1132, measure the resistance between PCM test pin 60 and PCM test pins 71 (VPWR) and 93 (HTR11).
  • For DTC 1152, measure the resistance between PCM test pin 87 and PCM test pins 71 (VPWR) and 94 (HTR21).
  • Is resistance greater than 10K ohms? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
Go to step 17.
No Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION .
Repair short to power.
Go to step 17.
6 CHECK FOR HO2S SIGNAL SHORTED TO HO2S HEATER CIRCUIT IN THE SENSOR
  • Connect suspect HO2S.
  • Key ON, Engine OFF (KOEO).
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Access O2S11 (Front RH) or O2S21 (Front LH) PID.
  • Is the HO2S voltage greater than 0.45 V? 
 Yes Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION .
Go to step 17.
No Connect all components.
Go to next step.
7 CHECK FUEL PRESSURE
WARNING:
  • The fuel system is pressurized when the engine is not running. To prevent injury or fire, use caution when working on the fuel system.
  • Connect battery charger.
  • Install fuel pressure gauge.
  • Key on, engine off (KOEO).
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select Active Command Modes.
  • Access output test mode and run the fuel pump to obtain maximum fuel pressure.
    NOTE:
    • The fuel pump will only operate for approximately 8 seconds when output test mode is selected and activated.
  • Is the fuel pressure 207-448 kPa (30-65 psi)? 
 Yes Fuel system is capable of required fuel pressure.
Go to next step.
No See GENERAL PINPOINT TEST 5: FUEL DELIVERY SYSTEM .
8 CHECK INJECTOR FAULT PIDS
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Access INJ1F-INJ16F PIDs.
  • Is an injector(s) fault present? 
 Yes Go to next step.
No Go to step 17.
9 CHECK FUEL INJECTOR(S) AND HARNESS RESISTANCE
NOTE:
  • This erases continuous memory DTCs.
  • Disconnect PCM.
  • Install breakout box, leave PCM disconnected.
NOTE:
  • Use the injector fault PID to determine the fuel injector circuit(s) requiring testing.
  • Measure resistance between suspect INJ circuit PCM test pin and PCM test pin 71 (VPWR).
  • Is the resistance between 11.0-18.0 ohms? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
Go to step 17.
No Go to next step.
10 CHECK FUEL INJECTOR HARNESS RESISTANCE
  • Disconnect fuel injector harness connector at the suspect fuel injector.
  • Measure resistance of VPWR circuit between PCM test pin 71 and the fuel injector harness connector.
  • Measure resistance of INJ circuit between appropriate PCM test pin and the fuel injector harness connector.
  • Is each resistance less than 5.0 ohms? 
 Yes Go to next step.
No Repair open harness circuit.
Go to step 17.
11 CHECK FUEL INJECTOR HARNESS CIRCUIT FOR SHORT TO POWER AND GROUND
  • Measure resistance between suspect INJ circuit PCM test pin and PCM test pin 71 (VPWR).
  • Measure resistance between suspect INJ circuit PCM test pin and PCM test pin 103 (PWR GND).
  • Is each resistance greater than 10K ohms? 
 Yes Go to next step.
No Repair short circuit.
Go to step 17.
12 FLOW TEST FUEL INJECTOR(S)
  • Use a fuel injector tester to flow test the fuel injectors according to the instructions for the tester.
    • Flow rate specification is 9.5 kg/hr (21 lb/hr) for 2.3L, 5.5 kg/hr (12 lb/hr) for 3.0L and 8.7 kg/hr (19 lb/hr) for 4.0L
  • Is the leakage and flow within specification? 
 Yes Go to next step.
No Replace fuel injector(s). See FUEL INJECTION SUPPLY MANIFOLD AND FUEL INJECTOR - 2.3L REMOVAL / INSTALLATIONFUEL INJECTION SUPPLY MANIFOLD AND FUEL INJECTOR - 3.0L REMOVAL / INSTALLATION or FUEL INJECTION SUPPLY MANIFOLD AND FUEL INJECTOR - 4.0L REMOVAL / INSTALLATION .
Go to step 17.
13 ATTEMPT TO GENERATE DTCS P1131 AND P1151
  • Disconnect suspect HO2S.
  • Jumper HO2S SIG at the HO2S harness vehicle connector to the battery negative post.
  • Perform key on, engine running (KOER) self-test.
  • Are DTCs P1131 or P1151 present? 
 Yes Remove jumper.
Go to next step.
No Remove jumper.
Disconnect PCM.
Inspect both ends for damaged or pushed out pins, corrosion and loose wires.
Repair as necessary.
If OK, replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
Go to step 17.
14 HO2S CHECK
  • Connect multimeter to HO2S SIG circuit and HO2S SIG RTN at the HO2S connector.
  • Disconnect any vacuum hose.
  • Start engine and run at 2, 000 rpm.
  • Does the voltage reading indicate less than 0.4 V within 30 seconds? 
 Yes Connect vacuum hose.
Go to next step.
No Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION .
Go to step 17.
15 MONITOR HO2S (PID) FOR PROPER SWITCHING
  • Key on, engine running (KOER).
  • Engine at operating temperature.
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Access O2S11 (Front RH) or O2S21 (Front LH) PID while wiggling, bending and shaking small sections of the engine harness from the HO2S to the PCM.
  • Key OFF.
  • Does the HO2S voltage stay high (greater than 0.45 V) or low (less than 0.45 V)? 
 Yes Isolate cause of lack of HO2S switching and repair as necessary.
Go to step 17.
No Go to next step.
16 TEST DRIVE WHILE MONITORING HO2S PID FOR PROPER SWITCHING
NOTE:
  • This step requires an observer to monitor PID for proper operation.
  • Access O2S11 (Front RH) or O2S21 (Front LH) HO2S PID.
  • While observer views PID, test drive vehicle under different road conditions in an attempt to simulate the original fault.
  • Does HO2S appear to switch properly? 
 Yes Unable to duplicate fault.
Go to next step.
No Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION .
Go to next step.
17 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Connect all disconnected connectors.
  • Clear DTCs from PCM memory using WDS or equivalent tester.
  • Perform PCM quick test.
  • Is same DTC present? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
Repeat PCM quick test.
No If any other DTC is present, go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) .
If no DTC is present, troubleshooting is complete.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.