What P0174 means
Diagnostic Trouble Code (DTC) P0174 stands for System Too Lean (Bank 2). This is a generic OBD2 diagnostic trouble code indicating that the engine computer (ECU) has registered an operational anomaly in the powertrain (p) systems.
When this error registers, the ECU records a freeze frame of sensor data and lights up the Check Engine Light on your dashboard to notify the operator of a system fault.
Symptoms of OBD2 Code P0174
When code P0174 is active, your car might exhibit the following common symptoms:
- Check Engine Light (MIL) active
- Rough idling or engine surging
- Stumbling upon acceleration
- Misfires under load (feels like engine stuttering)
Common Causes of Code P0174
Faults that trigger this code typically include:
- Cause 1: Vacuum leak affecting Bank 2 side of the manifold
- Cause 2: Dirty or failing Mass Air Flow (MAF) sensor
- Cause 3: Failing oxygen sensor on Bank 2
- Cause 4: Faulty or clogged fuel injectors on Bank 2 cylinders
Can you drive with a P0174 code?
No, similar to P0171, running lean on Bank 2 can cause engine pinging, overheating, and mechanical damage to pistons and exhaust valves.
Expected Repair Cost Band
Intake manifold gasket replacement ranges from $200 to $600. MAF sensor replacement is $100 - $250. Fuel injector cleaning or replacement is $150 - $400.
Related Diagnostic Trouble Codes
If you have scanned multiple codes, see these related guides for troubleshooting context:
Frequently Asked Questions
P0171 indicates a lean condition on Bank 1, whereas P0174 indicates a lean condition on Bank 2 (the side of the engine without Cylinder #1).
A loose gas cap generally causes evaporative emission codes (P0455/P0442), not a direct lean engine code like P0174.
You can inspect vacuum lines visually, use a smoke machine, or listen for a hissing sound while the engine is running.
Yes, a biased O2 sensor can falsely report a lean mixture, forcing the ECU to add unnecessary fuel and trigger the fault.
If the lean condition is caused by a slightly clogged injector, a high-quality fuel system cleaner may resolve it, but mechanical issues require physical repair.