P0173
Injector Circuit:
Connectors: A-21X, B-01, B-02, B-05, B-06, B-25, B-26, B-48, C-51 <M/T>, C-52 <A/T>:
Fuel Trim Circuit
CIRCUIT OPERATION
- The injector power is supplied from the MFI relay (terminal 1).
- The ECM
TECHNICAL DESCRIPTION
- If a malfunction occurs in the fuel system. the fuel trim value becomes too large or too small.
- The ECM
DTC SET CONDITIONS
Check Conditions
- Under the closed loop air/fuel ratio control.
- Intake air temperature is higher than -10°C (14°F).
- Barometric pressure sensor is higher than 76 kPa (11 psi).
- Volume air flow sensor output frequency is 100 Hz or more.
Judgment Criteria
- Long term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short term fuel trim has continued to be higher than +7.4 percent or lower than -7.4 percent for 5 seconds.
Check Conditions
- During closed loop air/fuel ratio control.
- Intake air temperature is higher than -10°C (14°F).
- Barometric pressure is higher than 76kPa (11 psi).
- Volume air flow sensor output frequency is 75 Hz or less.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +12.4 percent or lower than -12.4 percent for 5 seconds.
Check Conditions
- During closed loop air/fuel ratio control.
- Intake air temperature is higher than -10°C (14°F).
- Barometric pressure is higher than 76kPa (11 psi).
- Volume air flow sensor output frequency is 75 Hz or more.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +17.4 percent or lower than -7.4 percent for 5 seconds.
Check Conditions
- During closed loop air/fuel ratio control.
- Intake air temperature is higher than -10°C (14°F).
- Barometric pressure is higher than 76kPa (11 psi).
- Volume air flow sensor output frequency is 75 Hz or more.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +22.4 percent or lower than -12.4 percent for 5 seconds.
Check Conditions
- During closed loop air/fuel ratio control.
- The heated oxygen sensor (front) is active.
Judgment Criteria
- Long-term fuel trim has continued to be higher than +12.5 percent or lower than -12.5 percent for 5 seconds.
- Short-term fuel trim has continued to be higher than +25.0 percent or lower than -30.0 percent for 5 seconds.
TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Volume air flow sensor failed.
- Injector (Number 2, 4, 6) failed.
- Incorrect fuel pressure.
- Air drawn in from gaps in gasket, seals, etc.
- Left bank heated oxygen sensor failed.
- Engine coolant temperature sensor failed.
- Intake air temperature sensor failed.
- Barometric pressure sensor failed.
- Exhaust leak.
- Use of incorrect or contaminated fuel.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
STEP 1. Check the exhaust leaks.
If not malfunctioning, go to Step 2.
If malfunctioning, repair or replace it. Then go to Step 14.
STEP 2. Check the intake system vacuum leak.
If not malfunctioning, go to Step 3.
If malfunctioning, repair or replace it. Then go to Step 14.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
STEP 3. Using scan tool MB991502, check data list item 12: Volume Air Flow Sensor.
1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to the data reading mode for item 12, Volume Air Flow Sensor.
- When idling, between 17 and 46 Hz (between 2.2 and 5.7 g/s).
- When 2,500 r/min, between 63 and 103 Hz (between 9.0 and 14.7 g/s).
If within specifications, go to Step 4.
If not within specifications, refer to DTC P0100 - Volume Air Flow Circuit Malfunction.
STEP 4. Using scan tool MB991502, check data list item 13: Intake Air Temperature Sensor.
1. Turn the ignition switch to "ON" position.
2. Set scan tool MB991502 to the data reading mode for item 13, Intake Air Temperature Sensor.
- The intake air temperature and temperature displayed on the scan tool should be within 10%.
If they match, go to Step 5.
If they do not match, refer to DTC P0110 - Intake Air Temperature Circuit Malfunction.
STEP 5. Using scan tool MB991502, check data list item 21: Engine Coolant Temperature Sensor.
1. Turn the ignition switch to "ON" position.
2. Set scan tool MB991502 to the data reading mode for item 21, Engine Coolant Temperature Sensor.
- The engine coolant temperature and temperature displayed on the scan tool should be within 10%.
If they match, go to Step 6.
If they do not match, refer to DTC P0115 - Engine Coolant Temperature Circuit Malfunction.
STEP 6. Using scan tool MB991502, check data list item 25: Barometric Pressure Sensor.
1. Turn the ignition switch to "ON" position.
2. Set scan tool MB991502 to the data reading mode for item 25, Barometric Pressure Sensor.
- At an altitude of 0 m (0 feet.), 101 kPa.
- At an altitude of 600 m (1,969 feet.), 95 kPa.
- At an altitude of 1,200 m (3,937 feet.), 88 kPa.
- At an altitude of 1,800 m (5,906 feet.), 81 kPa.
If within specifications, go to Step 7.
If not within specifications, refer to DTC P0105 - Barometric Pressure Circuit Malfunction.
STEP 7. Check the left bank injector.
1. Disconnect the left bank injector connector.
2. Measure the resistance between injector side connector terminals 1 and 2.
Standard value: 13 - 16 ohms [at 20°C (68°F)]
If within specifications, go to Step 8.
If not within specifications, replace the injector. Then go to Step 14.
STEP 8. Check harness connectors B-02, B-06, B-25 at the left bank injector for damage.
If harness connectors B-02, B-06, B-25 are in good condition, go to Step 9.
If harness connectors B-02, B-06, B-25 are damaged, repair or replace them.
Refer to Harness Connector Inspection. Then go to Step 14.
STEP 9. Check harness connector C-51 at the ECM
If harness connector C-51
If harness connector C-51
Refer to Harness Connector Inspection. Then go to Step 14.
STEP 10. Check the harness wires between injector connectors B-02, B-06, B-25 and ECM connector C-51
If the wires between injector connectors B-02, B-06, B-25 and ECM connector C-51
If the wires between injector connectors B-02, B-06, B-25 and ECM connector C-51
STEP 11. Check the fuel pressure.
Refer to Fuel Pressure Test.
If correct, go to Step 12.
If incorrect, repair or replace it. Then go to Step 14.
STEP 12. Check for entry of foreign matter (water, kerosene, etc) into fuel.
If OK, go to Step 13.
If contaminated, replace the fuel. Then go to Step 14.
STEP 13. Replace the left bank injectors.
1. Replace the left bank injectors.
2. Carry out a test drive with the drive cycle pattern. Refer to Procedure 2 - Fuel Trim Monitor.
3. Check for the diagnostic trouble code (DTC).
If DTC P0173 is not output, the inspection is complete.
If DTC P0173 is not output, replace the ECM or PCM. Then go to Step 14.
STEP 14. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 2 - Fuel Trim Monitor.
2. Read the diagnostic trouble code, and confirm that diagnostic trouble code P0173 does not reset.