OBD-II diagnostic trouble code
P0174Caution
System Too Lean (Bank 2)
The same lean-mixture problem as P0171, but affecting bank 2 (the other cylinder bank on a V6/V8/V-configuration engine) rather than bank 1. On an inline engine, banks 1 and 2 don't apply the same way, so seeing this code specifically confirms a V-type or flat engine layout.
Symptoms
- Rough idle or a slight surge at idle
- Hesitation or reduced power under acceleration
- Occasional misfire on bank 2 cylinders specifically
- Often appears alongside P0171 if the cause is something shared, like a MAF sensor issue
Likely causes
- Vacuum leak on the bank 2 side of the intake
- A dirty or failing mass airflow (MAF) sensor — since this sensor affects the whole engine, it often causes both banks to trigger lean codes together
- Weak fuel pressure affecting bank 2's injectors more than bank 1's, depending on fuel rail design
- A clogged or underperforming injector on one of the bank 2 cylinders
How to diagnose it
- Check fuel trim values for both banks with a scan tool — if both banks show similar lean trims, suspect a shared cause like the MAF sensor; if only bank 2 is affected, focus there specifically
- Inspect bank 2 intake hoses and gaskets for leaks
- Check fuel pressure at the rail against spec
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Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.
Frequently asked questions
Can I drive with P0174?
You can usually keep driving with P0174, but don't put it off — the underlying cause can get worse or lead to further damage the longer it goes unaddressed. Get it diagnosed as soon as you reasonably can.
How much does it cost to fix P0174?
Typical repair costs for {code} range from roughly 50 to 600 EUR, depending on the specific cause and your car — see the fixes listed above for a breakdown.
What causes P0174?
Vacuum leak on the bank 2 side of the intake A dirty or failing mass airflow (MAF) sensor — since this sensor affects the whole engine, it often causes both banks to trigger lean codes together Weak fuel pressure affecting bank 2's injectors more than bank 1's, depending on fuel rail design
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief