P0174Moderate severityFuel/AirDIY: Moderate
P0174: System Too Lean (Bank 2)
Same idea as P0171 but on the opposite cylinder bank. When P0171 and P0174 appear together, suspect a shared problem like the MAF sensor or a big vacuum leak.
Can I keep driving?
Usually yes for short trips, but fix it soon. Running lean on one bank can lead to misfires and extra heat.
Symptoms you might notice
- Rough idle or stumbling at low speed
- Reduced power under load
- Check engine light, often alongside P0171
What to check first
- Check whether P0171 is stored too. Both banks lean at once points to something shared: the MAF sensor, a leak in the main intake path, or fuel pressure.
- If only P0174 is set, look at the intake side of bank 2 first: that side's intake gasket area and vacuum lines.
- Clean the MAF sensor with MAF-sensor cleaner and re-check fuel trim on a scan tool.
- Test fuel pressure if the air side checks out.
Most common causes
- Large vacuum or intake leak
- MAF sensor contamination
- Failing fuel pump
- Exhaust leak ahead of the front O2 sensor
Check it against your exact vehicle
A code means the same thing on every car, but where the parts are and what to check first depends on your year, make, model and engine. Tell CaliperAI what you are seeing and it will help narrow down the likely causes for your vehicle.
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General information about this code, not a diagnosis of your specific vehicle. Safety-critical work such as brakes, fuel and airbags is best left to a qualified mechanic.