What does it mean?
P1174 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Front Air/Fuel Ratio (A/F) Sensor (Bank 2, Sensor 1) Circuit Out of Range High .
Symptoms
- Check engine light on
- Bank 2 fuel control reverts to a default map while bank 1 keeps working normally
- Uneven idle and a noticeable difference in fuel trim between banks
- Reduced power and hesitation during acceleration
- Higher fuel consumption and a rich exhaust smell
- Readiness monitors will not complete
Likely causes
- Signal wire shorted to a voltage source through chafed insulation
- Open or high-resistance sensor ground allowing the signal to rise
- Failed sensing element inside the bank 2 air/fuel sensor
- Corrosion or moisture in the connector, which sits exposed at the front of the engine
- Terminal fretting or a loose crimp at a previous repair splice
- Heat damage to the harness where it passes the exhaust manifold
- Rarely, an internal module input failure
How to fix it
- Compare bank 1 and bank 2 sensor values in live data at idle and at cruise
- Disconnect the bank 2 sensor and see whether the module reports an open circuit as expected; no change points to wiring
- Check the signal wire for a short to voltage and the ground wire for continuity to the module
- Inspect the connector for melted plastic, green corrosion, and loose pin tension
- Examine the harness routing along the exhaust manifold and repair any heat damage
- If wiring measures good, replace the bank 2 air/fuel sensor with the correct specification part
- Clear codes, then confirm both banks respond together during a road test