P0171 System too Lean (bank 1)
Fuel Trim Circuit
Refer to DTC P0201 − P0206, Injector Circuit.
Check Conditions
Engine coolant temperature is lower than approximately 100°C (212°F) when the engine is started. Intake air temperature is lower than 60°C (140°F) when the engine is started. Under the closed loop air/fuel ratio control. Engine coolant temperature is higher than 77°C (171°F). Volume airflow sensor output frequency is 100 Hz or more.
Judgment Criteria
Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds or Short-term fuel trim has continued to be higher than +7.4 percent for 5 seconds.
Check Conditions
Engine coolant temperature is lower than approximately 100°C (212°F) when the engine is started. Intake air temperature is lower than 60°C (140°F) when the engine is started. Under the closed loop air/fuel ratio control. Engine coolant temperature is higher than 77°C (171°F). Volume airflow sensor output frequency is 100 Hz or less.
Judgment Criteria
Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds
or Short-term fuel trim has continued to be higher than +12.5 percent for 5 seconds.
Check Conditions
Engine coolant temperature is higher than approximately 100°C (212°F) when the engine is started. Intake air temperature is higher than 60°C (140°F) when the engine is started. Under the closed loop air/fuel ratio control. Engine coolant temperature is higher than 77°C (171°F). Volume airflow sensor output frequency is 100 Hz or more.
Judgment Criteria
Long-term fuel trim has continued to be higher than +12.5 percent or 5 seconds
or Short-term fuel trim has continued to be higher than +17.6 percent for 5 seconds.
Check Conditions
Engine coolant temperature is higher than approximately 100°C (212°F) when the engine is started. Intake air temperature is higher than 60°C (140°F) when the engine is started. Under the closed loop air/fuel ratio control. Engine coolant temperature is higher than 77°C (171°F). Volume airflow sensor output frequency is 100 Hz or less.
Judgment Criteria
Long-term fuel trim has continued to be higher than +12.5 percent or 5 seconds
or Short-term fuel trim has continued to be higher than +22.3 percent for 5 seconds.
Check Conditions
Engine coolant temperature is higher than 77°C (171°F). Under the closed loop air/fuel ratio control.
Judgment Criteria
Long-term fuel trim has continued to be +12.5 percent for 5 seconds or Short-term fuel trim has continued to be +25.0 percent for 5 seconds.
The most likely causes for this code to be set are:
- Volume airflow sensor failed.
- Injector (Number 1, 3, 5) failed.
- Incorrect fuel pressure.
- Air drawn in from gaps in gasket, seals, etc.
- Right 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.
- PCM failed.
Fuel Trim Circuit
Refer to DTC P0201 − P0206, Injector Circuit.
Check Conditions
Engine coolant temperature is lower than approximately 100°C (212°F) when the engine is started. Intake air temperature is lower than 60°C (140°F) when the engine is started. Under the closed loop air/fuel ratio control. Engine coolant temperature is higher than 77°C (171°F). Volume airflow sensor output frequency is 100 Hz or more.
Judgment Criteria
Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds or Short-term fuel trim has continued to be higher than +7.4 percent for 5 seconds.
Check Conditions
Engine coolant temperature is lower than approximately 100°C (212°F) when the engine is started. Intake air temperature is lower than 60°C (140°F) when the engine is started. Under the closed loop air/fuel ratio control. Engine coolant temperature is higher than 77°C (171°F). Volume airflow sensor output frequency is 100 Hz or less.
Judgment Criteria
Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds
or Short-term fuel trim has continued to be higher than +12.5 percent for 5 seconds.
Check Conditions
Engine coolant temperature is higher than approximately 100°C (212°F) when the engine is started. Intake air temperature is higher than 60°C (140°F) when the engine is started. Under the closed loop air/fuel ratio control. Engine coolant temperature is higher than 77°C (171°F). Volume airflow sensor output frequency is 100 Hz or more.
Judgment Criteria
Long-term fuel trim has continued to be higher than +12.5 percent or 5 seconds
or Short-term fuel trim has continued to be higher than +17.6 percent for 5 seconds.
Check Conditions
Engine coolant temperature is higher than approximately 100°C (212°F) when the engine is started. Intake air temperature is higher than 60°C (140°F) when the engine is started. Under the closed loop air/fuel ratio control. Engine coolant temperature is higher than 77°C (171°F). Volume airflow sensor output frequency is 100 Hz or less.
Judgment Criteria
Long-term fuel trim has continued to be higher than +12.5 percent or 5 seconds
or Short-term fuel trim has continued to be higher than +22.3 percent for 5 seconds.
Check Conditions
Engine coolant temperature is higher than 77°C (171°F). Under the closed loop air/fuel ratio control.
Judgment Criteria
Long-term fuel trim has continued to be +12.5 percent for 5 seconds or Short-term fuel trim has continued to be +25.0 percent for 5 seconds.
The most likely causes for this code to be set are:
- Volume airflow sensor failed.
- Injector (Number 1, 3, 5) failed.
- Incorrect fuel pressure.
- Air drawn in from gaps in gasket, seals, etc.
- Right 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.
- PCM failed.