P1151 — Lack of Upstream HO2S Switch — Indicates Lean (Bank 2)

What P1151 means

This is a manufacturer-specific code — its meaning depends on the vehicle’s make (see below).

What P1151 means on specific makes

Ford / Lincoln CAUTION

Same as P1131 but on bank 2 (the other cylinder bank on a V6/V8/V10). When P1131 and P1151 both set together, the cause is almost always something feeding BOTH banks — a dirty MAF or a big shared vacuum leak.

1. Dirty MAF sensor (affects both banks) ($0-150)
2. Vacuum leak ($0-200)
3. Low fuel pressure ($20-100)
4. Bank 2 upstream O2 sensor ($50-150)

Check first: If paired with P1131, suspect MAF or vacuum leak first — one shared cause. Check fuel trims on both banks.

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