Code No. P0172: Abnormal Fuel System (rich)

OPERATION

Check code No. P0261: No. 1 injector circuit low input (Refer to ).
Check code No. P0264: No. 2 injector circuit low input (Refer to ).
Check code No. P0267: No. 3 injector circuit low input (Refer to ).

FUNCTION

If the fuel system goes out of order, the fuel correction value will become larger.
The engine-ECU checks whether the fuel trim value is within a specified range.

TROUBLE JUDGEMENT

Check Conditions

Under the closed loop air/fuel ratio control.
Engine coolant temperature is more than 79°C.

Judgement Criterion

Long-term fuel trim is less than -12.5% for 5 seconds.

or

Short-term fuel trim is less than -10.2% for 5 seconds.

Check Conditions

Under the closed loop air/fuel ratio control.
Engine coolant temperature is more than 79°C.

Judgement Criterion

Long-term fuel trim is less than -12.5% for 5 seconds.

or

Short-term fuel trim is less than -15.2% for 5 seconds.

Check Conditions

Engine coolant temperature is more than 79°C.
Under the closed loop air/fuel ratio control.

Judgement Criterion

Long-term fuel trim is -12.5% for 2 seconds.

or

Short-term fuel trim is -25.0% for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION

None

PROBABLE CAUSES

Failed intake air temperature sensor
Failed engine coolant temperature sensor
Failed manifold absolute pressure sensor
Failed injector
Failed fuel supply system (such as failed fuel pressure)
Entry of foreign material to fuel (such as water, diesel fuel, water removers and additive)
Harness damage in oxygen sensor circuit, or connector damage
Failed oxygen sensor (front)
Failed installation of oxygen sensor (front)
Failed engine-ECU

DIAGNOSIS PROCEDURE

*: Preparation to carry out troubleshooting

STEP 1. M.U.T.-III diagnosis code

Q. Is any other diagnosis code than P0172 stored?

	Inspection Chart for Diagnosis Code

	Go to Step 2.

STEP 2. M.U.T.-III data list

Refer to Data List Reference Table .

Item No. 6: Intake air temperature sensor
Item No. 7: Manifold absolute pressure sensor
Item No. 8: Engine coolant temperature sensor

Q. Are the check results normal?

	Go to Step 3.

	Perform the diagnosis code classified check procedure for the sensor that has shown an abnormal data value (Refer to Inspection Chart for Diagnosis Code ).

STEP 3. Check installation status of oxygen sensor (front).

Q. Is the check result normal?

	Go to Step 4.

	Repair.

STEP 4. Check of damage in O2FL, OFLE line between oxygen sensor (front) connector and engine-ECU connector

Q. Is the check result normal?

	Go to Step 5.

	Repair the connector(s) or wiring harness.

STEP 5. Measure fuel pressure

Measure fuel pressure (Refer to Fuel Pressure Test ).

Q. Is the check result normal?

	Go to Step 6.

	Repair the fuel pressure.

STEP 6. Check injector itself.

Check injector itself (Refer to ).

Q. Is the check result normal?

	Go to Step 7.

	Replace the injector.

STEP 7. Check fuel.

Check whether foreign materials enter into fuel such as water, diesel fuel, water removers and additives.

Q. Is the check result normal?

	Go to Step 8.

	Replace the fuel.

STEP 8. M.U.T.-III data list.

Refer to Data List Reference Table .

Item No. 11: Oxygen sensor

Q. Is the check result normal?

	Go to Step 9.

	Replace the oxygen sensor.

STEP 9. After checking stored freeze frame data, check diagnosis codes again.

If diagnosis code P0172 is stored while the vehicle is idling, let the vehicle idle for more than 20 minutes.
If diagnosis code P0172 is stored while the vehicle is running, let the vehicle run with the same conditions of the freeze frame data, such as the vehicle speed, the crank angle sensor and the coolant temperature sensor, for more than 10 minutes.

Q. Is the diagnosis code P0172 stored?

	After replacing the oxygen sensor (front), go to Step 10.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

STEP 10. After checking stored freeze frame data, check diagnosis codes again.

If diagnosis code P0172 is stored while the vehicle is idling, let the vehicle idle for more than 20 minutes.
If diagnosis code P0172 is stored while the vehicle is running, let the vehicle run with the same conditions of the freeze frame data, such as the vehicle speed, the crank angle sensor and the coolant temperature sensor, for more than 10 minutes.

Q. Is the diagnosis code P0172 stored?

	Replace the engine-ECU.

	Check end.