P0174: System Too Lean (Bank 2)
Bank 2 of your engine is running lean - too much air, not enough fuel. On V6/V8 engines, Bank 2 is the side opposite the #1 cylinder. Often occurs together with P0171 (Bank 1 lean) pointing to a system-wide issue.
Symptoms
- Check engine light
- Rough idle
- Hesitation on acceleration
- May occur with P0171
Causes (Ranked by Likelihood)
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DIY Fix Steps
⚠ Safety first: work on a cold engine, chock wheels, use jack stands - never rely on a floor jack alone.
Both banks lean = MAF sensor or fuel delivery issue. Single bank lean = vacuum leak or injector issue on that bank.
Most common fix. Spray MAF cleaner on sensing element. Let dry 20 minutes. Clear codes, drive 2 cycles.
PCV valve and hose are a frequent vacuum leak source that affects both banks. PCV valve costs $5-20 and is easy to replace.
Low fuel pressure affects all cylinders. Normal range: 40-65 PSI depending on engine. Check with $25 fuel pressure gauge.