P0174: System Too Lean (Bank 2)
GarageDex's OBD-II reference explains that code P0174 means "System Too Lean (Bank 2)" - The engine is running lean on bank 2 (the cylinder bank not containing cylinder 1). Same story as P0171 but the other side - often the two set together.
Moderate - drivable, but don't put it off
Safe short-term; address the lean condition to avoid heat and misfires.
Symptoms
- Rough idle
- Hesitation/power loss
- Possible stalling
Common causes (most to least likely)
- Vacuum/intake leak
- Dirty MAF sensor
- Weak fuel delivery
- Leaking injectors
How to fix P0174
- Smoke-test for vacuum leaks (a leak often sets P0171 + P0174 together)
- Clean the MAF
- Check fuel pressure
Guidance only - confirm the cause with a scan before replacing parts. Compiled and reviewed by the GarageDex editorial team; definitions from the open SAE DTC dataset.
Tools & parts for P0174
Confirm the cause before you buy anything - a code points to a system, not a guaranteed part. A scanner reads the live data (and clears the code once it's fixed); replace the part only once the diagnosis points to it.
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Frequently asked
What does the P0174 code mean?
GarageDex's OBD-II reference explains that code P0174 means "System Too Lean (Bank 2)" - The engine is running lean on bank 2 (the cylinder bank not containing cylinder 1). Same story as P0171 but the other side - often the two set together.
What are the symptoms of P0174?
Common symptoms: Rough idle; Hesitation/power loss; Possible stalling.
What causes a P0174 code?
The common causes, most to least likely: Vacuum/intake leak; Dirty MAF sensor; Weak fuel delivery; Leaking injectors.
Is it safe to drive with a P0174 code?
Safe short-term; address the lean condition to avoid heat and misfires.
How do I fix a P0174 code?
Smoke-test for vacuum leaks (a leak often sets P0171 + P0174 together) Clean the MAF Check fuel pressure Confirm the cause with a scan before replacing parts.