H - Test
H: Fuel Control
H: Introduction H - Introduction
-------------------------------------------------
H1 DIAGNOSTIC TROUBLE CODES (DTCS) P0171, P0172, P2195, P2196, P2270, AND P2271: CHECK FOR SELF-TEST DTCS
Are any of the following DTCs present during PCM or transaxle control module (TCM) self-test: P0171, P0172, P2195, P2196, P2270, or P2271?
YES
For DTCs P2270 or P2271, GO to H17
.
For DTCs P0171 or P2195, GO to H2
.
For DTCs P0172 or P2196, GO to H7.
NO
For all others, GO to Diagnostic Trouble Code (DTC) Charts and Descriptions Diagnostic Trouble Code Descriptions.
-------------------------------------------------
H2 DTCS P0171 OR P2195: LEAN SYSTEM DTCS
Note: Do not clear the DTCs or reset the keep alive memory (KAM).
- Access the PCM and record the ECT PID from the freeze frame data. The freeze frame data is used to recreate the concern.
- Retrieve and record the self-test DTCs.
Are any DTCs present other than P0171 or P2195?
YES
DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to Diagnostic Trouble Code (DTC) Charts and Descriptions Diagnostic Trouble Code Descriptions.
NO
GO to H3.
-------------------------------------------------
H3 CARRY OUT A VISUAL INSPECTION ON THE INTAKE AIR SYSTEM AND ALL VACUUM HOSES
- Key in OFF position.
- 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 H6.
NO
GO to H4.
-------------------------------------------------
H4 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: When calculating the total fuel correction in the following steps, if LONGFT1 equals +13% and SHRTFT1 equals +23%, the total fuel correction for bank 1 equals +36%. If LONGFT1 equals +24% and SHRTFT1 equals -3% the total fuel correction for bank 1 equals +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 the PCM and monitor the ECT, CHT and IAT PIDs.
- Access the PCM and monitor the LONGFT1 and SHRTFT1 PIDs.
- Allow the engine to stabilize at the temperature necessary to recreate the concern.
- Mathematically add and record the LONGFT PID value to the SHRTFT PID value, for a total fuel correction at idle.
- Increase the engine speed to 2,500 RPM for 10 seconds.
- Record the LONGFT1 and SHRTFT1 PID values.
- Mathematically add and record the LONGFT PID value to the SHRTFT PID value, for a total fuel correction at 2,500 RPM.
Is the total fuel correction value difference, between idle and 2,500 RPM, less than 15 percent?
YES
No vacuum leak is present.
For DTC P0171, GO to H10
.
For DTC P2195, GO to H9.
NO
GO to H5.
-------------------------------------------------
H5 LOCATE THE VACUUM LEAK
NOTICE: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: When monitoring for a decrease in the SHRTFT1 PID in the following steps, if SHRTFT1 is +15%, but when the hose is restricted SHRTFT1 decreases to -7%, the decrease in the SHRTFT1 PID equals 22%.
- Locate the vacuum tees for the intake air and PCV systems.
- Access the PCM and monitor the SHRTFT1 PID.
- Restrict the vacuum lines one at a time for 30 seconds. If a vacuum leak is present, the SHRTFT1 PID value decreases as the hose is restricted.
Is the decrease in the SHRTFT1 PID greater than 15 percent when one of the vacuum hoses is restricted?
YES
GO to H6.
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 H6.
-------------------------------------------------
H6 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 the PCM and monitor the SHRTFT1 PID.
- Allow the engine to stabilize at the temperature necessary to recreate the concern.
- Record the SHRTFT1 PID value.
- Key in OFF position.
- Repair the vacuum leak.
- Key ON, engine running.
- Allow the engine to stabilize at the temperature necessary to recreate the concern.
- Access the PCM and monitor the SHRTFT1 PID.
- Compare the recorded SHRTFT1 PID value, prior to the vacuum leak repair, to the current SHRTFT1 PID value.
Is the decrease in the SHRTFT1 PID greater than 15 percent?
YES
RESET the keep alive memory (KAM). REFER to Resetting The Keep Alive Memory (KAM) Resetting The Keep Alive Memory (KAM).
NO
A vacuum leak is still present.
GO to H5.
-------------------------------------------------
H7 DTCS P0172 OR P2196: RICH SYSTEM DTCS
Note: Do not clear the DTCs or reset the KAM.
- Access the PCM and record the freeze frame data.
- Retrieve and record the self-test DTCs.
Are any DTCs present other than P0172 or P2196?
YES
DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to Diagnostic Trouble Code (DTC) Charts and Descriptions Diagnostic Trouble Code Descriptions.
NO
GO to H8.
-------------------------------------------------
H8 INSPECT THE ENTIRE INTAKE AIR SYSTEM FOR DEBRIS, BLOCKAGE OR OTHER DAMAGE
- Check the intake air system for obstructions, restrictions, and damage.
- Check the air filter element and housing for blockage.
Is a concern present?
YES
REPAIR as necessary.
CLEAR the DTCs. REPEAT the self-test.
NO
For DTC P0172, GO to H10
.
For DTC P2196, GO to H9.
-------------------------------------------------
H9 CHECK THE UO2SPC CIRCUIT FOR AN OPEN IN THE HARNESS
Note: Only the suspect UO2S needs to be diagnosed.
- Key in OFF position.
- Universal HO2S connector disconnected.
- PCM connector disconnected.
- Measure the resistance between:
Is the resistance less than 5 ohms?
YES
GO to H10.
NO
REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
H10 CHECK THE FUEL PRESSURE
WARNING: WHEN CHECKING THE FUEL SYSTEM REMEMBER THAT THE FUEL SYSTEM MAY STILL BE PRESSURIZED WHEN THE ENGINE IS SWITCHED OFF. ALWAYS FOLLOW THE INSTRUCTIONS RELATED TO FUEL SYSTEM PRESSURE RELIEF. ALL FUEL HANDLING SAFETY PRECAUTIONS MUST BE OBSERVED. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.
- Key in OFF position.
- Carry out the fuel system pressure test. REFER to Fuel System for the Fuel System Pressure Test procedure.
Is the key ON, engine OFF fuel system pressure between 262 - 448 kPa (38 - 65 psi)?
YES
GO to H11.
NO
GO to Pinpoint Test HC HC - Introduction.
-------------------------------------------------
H11 CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY - FAST LEAKDOWN
Note: When the fuel pump is commanded off, the fuel pressure may substantially decrease and then stabilize.
Note: During output state control, the fuel pump stays commanded on for only about 5 seconds.
- Key in OFF position.
- Key ON, engine OFF.
- Access the PCM and control the FP PID.
- Run the fuel pump to obtain maximum fuel pressure.
- Command the fuel pump off.
- Allow the fuel pressure to stabilize.
- Record the stabilized reading.
- Monitor the fuel pressure for 10 seconds.
Does the fuel pressure remain within 34 kPa (5 psi) of the recorded reading after 10 seconds?
YES
GO to H13.
NO
GO to H12.
-------------------------------------------------
H12 CHECK FOR AN EXTERNAL FUEL LEAK
- Inspect the fuel tank, lines, and filler pipe for a fuel leak.
Is a concern present?
YES
REPAIR as necessary.
REFER to the fuel system WARNING information at the beginning of Pinpoint Test HC. GO to Pinpoint Test HC HC - Introduction
.
CLEAR the DTCs. REPEAT the self-test.
NO
GO to H16.
-------------------------------------------------
H13 CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY - SLOW LEAKDOWN
- Continue to monitor the fuel pressure for 1 minute.
Does the fuel pressure remain within 34 kPa (5 psi) of the recorded reading after 1 minute?
YES
GO to H16.
NO
GO to HC6 HC - Test.
-------------------------------------------------
H14 CHECK THE SEPARATION LEVEL OF THE ETHANOL/WATER MIXTURE AND GASOLINE IN THE FUEL
Note: This step requires the use of a locally obtained 200 ml beaker and a 25 ml graduated cylinder.
Note: After approximately 3 minutes of standing, the ethanol and water mixes together and settles to the bottom of the 25 ml graduated cylinder. The gasoline rises to the top.
- Fill the 200 ml beaker with 5 ml of clean water.
- Use the pressure relief valve on the mechanical fuel gauge to drain 22 ml of fuel into an approved clean container.
- Pour 20 ml of fuel from the approved clean container into the 25 ml graduated cylinder.
- Add enough water from the 200 ml beaker to the 25 ml graduated cylinder to bring the total volume of liquid to 24 ml.
- Insert a stopper plug in the opening of the 25 ml graduated cylinder.
- Firmly hold the stopper in place and shake the 25 ml graduated cylinder to mix the water and fuel.
- Allow the liquid to stand and separate for approximately 3 minutes.
- Record the separation level from the 25 ml graduated cylinder where the ethanol/water mixture and gasoline meet.
Did the ethanol/water mixture and gasoline separate?
YES
GO to H15.
NO
COMPLETE all steps before continuing. The ethanol/water mixture separates from the gasoline. If the fuel does not appear to separate, then the fuel is either 100% ethanol or a mixture of ethanol and water.
-------------------------------------------------
H15 CALCULATE THE PERCENTAGE OF ETHANOL IN THE FUEL
Note: Use the illustration as an example for calculating the percentage of ethanol in the following steps. If the separation level is at 14 ml the calculation becomes; 14 minus 4, then multiply by 5 to equal 50. The percentage of ethanol in the fuel is 50%.
- Key in OFF position.
- Take the recorded separation level from the previous step and subtract the amount of water added.
- Multiply the new value by 5. This new value is the percentage of ethanol in the fuel.
- Record the calculated percentage of ethanol in the fuel.
Is the calculated percentage of ethanol in the fuel less than 25%?
YES
GO to H16.
NO
REPAIR as necessary. ADVISE the customer of the correct fuel type required for this vehicle. REFER to the Owner's Literature for additional information.
CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
H16 FLOW TEST
- Key in OFF position.
- PCM connector connected.
- Check the fuel injectors for leakage and flow rate using the injector flow tester or other method such as inspecting the intake manifold for fuel.
Are the test results satisfactory?
YES
GO to DC26 DC - Test.
NO
INSTALL a new fuel injector. REFER to Fuel Charging and Controls.
RESET the KAM. REFER to Resetting The Keep Alive Memory (KAM) Resetting The Keep Alive Memory (KAM). REPEAT the self-test.
-------------------------------------------------
H17 DTCS P2270 OR P2271: HO2S LACK OF SWITCHES STUCK LEAN OR RICH
Note: Address all continuous memory ignition and misfire DTCs before any KOER HO2S DTCs.
- Key in OFF position.
- Visually inspect for:
- pinched, shorted, and corroded wiring and pins
- oil or water contamination
- crossed sensor wires
- contaminated or damaged sensor
Is a concern present?
YES
REPAIR as necessary.
CLEAR the DTCs. REPEAT the self-test.
NO
For KOER DTCs P2270 or P2271, GO to H19
.
For continuous memory DTCs P2270 or P2271, GO to H18.
-------------------------------------------------
H18 CHECK FOR KOER DTCS
- Key ON, engine OFF.
- Clear the DTCs.
- Key ON, engine running.
- Run the engine at approximately 2,000 RPM. Maintain the engine speed for 3 minutes.
- Retrieve the continuous memory DTCs.
Are DTCs P2270 or P2271 present?
YES
GO to H19.
NO
Unable to duplicate or identify the concern at this time.
GO to Pinpoint Test Z Z - Introduction.
-------------------------------------------------
H19 CHECK THE HO2S SIGNAL LEVEL TOO HIGH
Note: Fuel calculations can be affected by unmetered air leaks.
- Key in OFF position.
- Carefully inspect the following areas for potential air leaks:
- hoses connecting to the mass air flow (MAF) sensor assembly
- hoses connecting to the throttle body
- intake manifold gasket leaks
- PCV disconnected.
- the vacuum lines are disconnected
- improperly seated engine oil dipstick, tube or oil fill cap
- exhaust leaks at flanges and gaskets
- With the vehicle in NEUTRAL, position it on a hoist. REFER to 100-02 Jacking and Lifting for the locations of the lifting points.
- Visually inspect for:
- exhaust leaks at flanges and gaskets
- HO2S not tightened to specification
- physical exhaust system concerns
- aftermarket exhaust
- punctures or cracks in the catalyst
Is a concern present?
YES
REPAIR as necessary.
CLEAR the DTCs. REPEAT the self-test.
NO
GO to H20.
-------------------------------------------------
H20 CHECK FOR SHORTS BETWEEN CIRCUITS IN THE HO2S HARNESS
- PCM connector disconnected.
- HO2S connector disconnected.
- Measure the resistance between:
- Measure the resistance between:
Are the resistances greater than 10K ohms?
YES
GO to H21.
NO
REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
H21 CHECK THE HO2S CIRCUIT FOR AN OPEN IN THE HARNESS
- Measure the resistance between:
Are the resistances less than 5 ohms?
YES
GO to H22.
NO
REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
H22 CHECK THE HO2S CIRCUIT VOLTAGE
- PCM connector connected.
- HO2S connector connected.
- Key ON, engine running.
- Access the PCM and monitor the O2S12 PID.
Is the voltage greater than 1.5 V?
YES
GO to H24.
NO
GO to H23.
-------------------------------------------------
H23 CHECK THE HO2S CIRCUIT VOLTAGE
- Key in OFF position.
- PCM connector connected.
- HO2S connector disconnected.
- Connect a 5 amp fused jumper wire between the following:
- Key ON, engine OFF.
- Access the PCM and monitor the O2S12 PID.
Is the voltage greater than 1.5 V?
YES
INSTALL a new HO2S. REFER to Electronic Engine Controls.
RESET the KAM. REFER to Resetting The Keep Alive Memory (KAM) Resetting The Keep Alive Memory (KAM). REPEAT the self-test.
NO
GO to H25.
-------------------------------------------------
H24 CHECK FOR OVER VOLTAGE IN THE PCM
- Key in OFF position.
- HO2S connector disconnected.
- Key ON, engine OFF.
- Measure the voltage between:
Are the voltages less than 1.5 V?
YES
INSTALL a new HO2S. REFER to Electronic Engine Controls.
RESET the KAM. REFER to Resetting The Keep Alive Memory (KAM) Resetting The Keep Alive Memory (KAM). REPEAT the self-test.
NO
GO to H25.
-------------------------------------------------
H25 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Visually inspect for:
- pushed out pins
- corrosion
- Connect all the PCM connectors and make sure they seat correctly.
- Carry out the PCM self-test and verify the concern is still present.
Is the concern still present?
YES
INSTALL a new PCM. REFER to Flash Electrically Erasable Programmable Read Only Memory (EEPROM) Flash Electrically Erasable Programmable Read Only Memory (EEPROM), Programming the VID Block for a Replacement PCM.
NO
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.