Error Code P0174
Moderate Issue
DTC Code P0174 indicates a Fuel Trim System Lean condition on Bank 2, where the Engine Control Module (ECM) detects a lean air/fuel mixture and adjusts fuel delivery to compensate.
What symptoms indicate Error Code P0174?
- Engine Light ON: The check engine light or service engine soon warning light illuminates, indicating an issue with the fuel trim system on bank 2. This is often linked to a lean condition where the air-fuel mixture is too lean.
- Excessive Fuel Consumption: The vehicle may experience higher than normal fuel consumption due to the engine compensating for the lean condition by injecting more fuel.
What causes OBD code Error Code P0174?
- Dirty or restricted air filters can limit airflow, causing the engine to run lean.
- A dirty or faulty Mass Air Flow (MAF) sensor can send incorrect air measurement data to the ECU, affecting fuel trim.
- Intake air leaks can introduce unmetered air, leading to a lean condition.
- Exhaust gas leaks before the oxygen sensor can skew sensor readings, causing incorrect fuel adjustments.
- Fuel contamination can affect combustion efficiency, leading to lean conditions.
- Faulty or clogged fuel injectors can restrict fuel delivery, causing a lean mixture.
- A faulty front heated oxygen sensor can provide inaccurate data, affecting fuel trim adjustments.
- Ignition misfiring can result in unburned oxygen in the exhaust, leading to a lean reading.
- Low fuel pressure can reduce fuel delivery, causing a lean condition.
- Positive Crankcase Ventilation (PCV) hose leaks can introduce unmetered air, affecting the air-fuel ratio.
How to fix OBD code Error Code P0174?
- Initial Inspection: Begin by checking for any additional DTCs, especially P0171, which often accompanies P0174. This can indicate a common issue such as an intake leak.
- Inspect for Intake Leaks: Examine the intake system for any vacuum leaks, cracked hoses, or loose connections. Use a smoke machine to detect any leaks that are not visible to the naked eye.
- Check Air Filter: Inspect the air filter for dirt or obstructions. Replace it if necessary to ensure proper airflow to the engine.
- Clean MAF Sensor: Remove and clean the Mass Air Flow (MAF) sensor using a dedicated MAF cleaner. Ensure it is free from dirt and debris that could affect its readings.
- Test MAF Sensor: If cleaning does not resolve the issue, test the MAF sensor for proper operation using a multimeter or scan tool to check for correct voltage and frequency readings.
- Inspect O2 Sensor: Check the Front Heated Oxygen (O2) sensor for proper function. Use a scan tool to monitor the sensor's voltage and response time.
- Replace Faulty Components: If the MAF or O2 sensor is found to be faulty, replace the defective component. Clear the DTC and perform a test drive to ensure the issue is resolved.