Ford P1151: HO2S Lean (Bank 2) — Fix
On Ford vehicles, P1151 means the upstream heated oxygen sensor on bank 2 is indicating a lean condition — the same lean fault as P1131 but on the other cylinder bank.
- Applies to
- Ford vehicles
- Est. repair cost
- $40 – $400
- Time to fix
- 30 minutes – 2 hours
What it means
Causes include a vacuum/intake leak, low fuel pressure, a dirty MAF, or an aged bank 2 O2 sensor. P1xxx codes are manufacturer-specific — P1151 is defined by Ford (not part of the generic SAE J2012 set), so this definition applies to Ford vehicles. Model years can vary, so confirm against the Ford service manual. Fix the fault, then clear the code with a scan tool.
Symptoms
- Check engine light on
- Rough idle or hesitation
- Poor fuel economy
How to fix it
- 1
Check for lean causes on bank 2
1. Inspect for vacuum/intake leaks and clean the MAF. 2. Test fuel pressure.
- 2
Test/replace the O2 sensor
1. Replace a lazy bank 2 upstream O2 sensor if the mixture is correct, then clear the code.
Frequently asked questions
Where is bank 2 on my Ford?
It's the cylinder bank that does not contain cylinder 1 on a V6/V8. P1151 is the lean reading on that side.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.