Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.
Measure resistance of the HO2S SIG circuit and HO2S Signal Return circuit between the PCM harness connector pin and the HO2S harness connector.
Is the resistance less than 5.0 ohms? Yes
REPLACE HO2S.
No
REPAIR as necessary.
H30 DTCS P0135 AND P0155: HO2S HEATER CIRCUIT IS SHORTED TO GROUND, SHORTED TO VPWR OR EXCESSIVE CURRENT DRAW, LOW CURRENT DRAW
Note: Refer to the PCM harness connector pin numbers in the beginning of this pinpoint test.
DTC/HO2S Reference List:
DTC P0135 = HO2S HTR-11
DTC P0155 = HO2S HTR-21
Note: On some applications, a vehicle hoist is required to access the HO2S harness.
Visually inspect the HO2S circuit for exposed wiring, water contamination, corrosion and proper assembly.
Were any concerns found during inspection? Yes
REPAIR any concerns found during inspection.
No
GO to H31
.
H31 PERFORM KEY ON ENGINE OFF (KOEO) SELF-TEST
Key on, engine off.
Perform KOEO Self-Test.
Is DTCs P0135, P0141, P0155 or P0161 present? Yes
KEY OFF. GO to H32
.
No
KEY OFF. GO to H33
.
H32 CHECK VPWR VOLTAGE TO HO2S HARNESS CONNECTOR
Note: If DTCs P0135 and P0155 or P0141 and P0161 are displayed, both heater circuits will require testing. DTCs displayed separately are to be tested individually.
Disconnect the appropriate HO2S(s).
Key on, engine off.
Measure voltage between VPWR and SIG RTN circuits at the HO2S harness connector.
Is the voltage greater than 10.5 volts? Yes
KEY OFF. GO to H33
.
No
CHECK fuse in circuit. If fuse is OK, REPAIR open circuit.
For no VPWR on vehicles equipped with 150 Pin PCM:
H41 CARRY OUT A VISUAL INSPECTION OF THE INTAKE AIR SYSTEM AND ALL VACUUM HOSES
Check the intake air system for leaks, obstructions, and damage.
Inspect the entire length of all the vacuum hoses for:
proper connections.
damage or cracks.
damaged or cracked vacuum tees.
Verify the integrity of the positive crankcase ventilation (PCV) system.
Verify the proper PCV valve part number.
Is a concern present? Yes
GO to H44
.
No
GO to H42
.
H42 CHECK FOR THE PRESENCE OF A VACUUM LEAK
Note: Fuel trim values at idle are more sensitive to a vacuum leak. The vacuum leak (unmetered air) represents a larger portion of the total air flow at idle than at part throttle. Note: The barometric pressure (BARO) PID is not a recommended PID to monitor when diagnosing a vacuum leak. Barometric pressure is calculated during high engine load, when the vacuum leak represents a small portion of the total air flow. Note: As an example, when calculating the total fuel correction in the following steps, if LONGFT1 = +13% and SHRTFT1 = +23%, the total fuel correction for bank 1 = +36%, also if LONGFT2 = +24% and SHRTFT2 = -3% the total fuel correction for bank 2 = +21%. Note: If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82°C - 101°C (180°F - 215°F) and the intake air temperature less than 46°C (115°F).
Key on, engine running.
Access and monitor the ECT or CHT, IAT, LONGFT1, SHRTFT1, LONGFT2 and SHRTFT2 PIDs.
Allow the engine to stabilize at the temperature necessary to recreate the concern.
Add and record the LONGFT PID value to the SHRTFT PID value for each bank, for a total fuel correction at idle.
Increase the engine speed to 2500 rpm for 10 seconds.
Record the LONGFT1, SHRTFT1, LONGFT2, and SHRTFT2 PID values.
Add and record the LONGFT PID value to the SHRTFT PID value for each bank, for a total fuel correction at 2500 rpm.
Is the total fuel correction value change, between idle and 2500 rpm, less than 15 percent? Yes
No vacuum leak is present.
GO to H47
.
No
GO to H43
.
H43 LOCATE THE VACUUM LEAK
CAUTION: Do not clamp or pinch a hard plastic hose. Use a vacuum cap or equivalent to restrict the hose. Note: Restricting the EVAP vapor hose while the EVAP emission canister is purging may shift the SHRTFT. Carry out a visual inspection as necessary. Note: As an example, when monitoring for a decrease in the SHRTFT PIDs in the following steps, if SHRTFT1 is +15%, but when the hose is restricted SHRTFT1 decrease to -7%, the decrease in the SHRTFT PIDs = 22 percent.
Locate the vacuum tees for the intake air and PCV systems.
Access and monitor the SHRTFT1 and SHRTFT2 PIDs.
Restrict the vacuum lines one at a time for 30 seconds. If a vacuum leak is present, the SHRTFT PID values will decrease as the hose is restricted.
Is the decrease in the SHRTFT PIDs greater than 15 percent when one of the vacuum hoses is restricted? Yes
GO to H44
.
No
INSPECT the intake air system for a vacuum leak in the intake manifold or intake gaskets. REPAIR as necessary.
For repair verification, GO to H44
.
H44 VACUUM LEAK REPAIR VERIFICATION
Note: If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82°C - 101°C (180°F - 215°F) and the intake air temperature less than 46°C (115°F).
Access and monitor the SHRTFT1 and SHRTFT2 PIDs.
Allow the engine to stabilize at the temperature necessary to recreate the concern.
Record the SHRTFT1 and SHRTFT2 PID values.
Key off.
Repair the vacuum leak.
Key on, engine running.
Allow the engine to stabilize at the temperature necessary to recreate the concern.
Access and monitor the SHRTFT1 and SHRTFT2 PIDs.
Compare the recorded SHRTFT PID values, prior to the vacuum leak repair, to the current SHRTFT PID values.
Is the decrease in the SHRTFT PIDs greater than 15 percent? Yes
H45 DTCs P1132 AND P1152: UPSTREAM HO2S NOT SWITCHING.
Note: It is necessary to address all Continuous Memory Ignition and Misfire DTCs, if received during Continuous Memory testing, before addressing any KOER HO2S DTCs.
DTC/HO2S Reference List:
HO2S-11 = DTC P1132
HO2S-21 = DTC P1152
Check intake air system for leaks, obstructions and damage.
H46 DTCs P0172 AND P0175: FUEL SYSTEM AT THE CORRECTED FUEL TRIM
Note: It is necessary to address all Continuous Memory Ignition and Misfire DTCs, if received during Continuous Memory testing, before addressing any Fuel Trim DTCs.
Fuel System DTC Reference List:
Bank 1 = DTC P0172 (rich)
Bank 2 = DTC P0175 (rich)
Check intake air system for leaks, obstructions and damage.