OBD-II Code
P1151
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$25–$1,400
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P1151 is the Bank 2 Sensor 1 mirror of P1131 — the upstream O2 on the driver side of most Ford V8s is reporting a persistent lean condition with insufficient rich/lean switching.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP1151 is the Bank 2 Sensor 1 mirror of P1131 — the upstream O2 on the driver side of most Ford V8s is reporting a persistent lean condition with insu…
P1151 is the Bank 2 Sensor 1 mirror of P1131 — the upstream O2 on the driver side of most Ford V8s is reporting a persistent lean condition with insufficient rich/lean switching. Same fundamental issue as P1131, opposite bank, and on Modular 4.6L/5.4L engines a P1131 plus P1151 set together almost always points to a shared vacuum source rather than two simultaneous O2 sensor failures.
Cheapest-first ladder
- read LTFT Bank 2 — above plus-10 percent confirms real lean (spec is plus or minus 8 percent at idle); compare to LTFT Bank 1.
- If both banks read plus-12 percent or higher equally, the leak is on a shared intake source like the upper plenum gasket, the throttle body gasket, the brake booster hose, or the EVAP purge solenoid stuck open.
- If only Bank 2 is lean, smoke-test driver-side intake runners and the rear PCV vacuum tee that feeds the brake booster on 5.4L Tritons.
- The expensive misdiagnosis is replacing the driver-side O2 and exhaust manifold based on the lean code when the actual fault is a $25 brake booster hose feeding both banks unmetered air.
Vehicle-specific patterns1999-2004 Ford F-150/Expedition 5.4L 2V trucks crack the plastic intake manifold on the driver side around the coolant crossover — Ford TSB 06-26-3 c…
- 1999-2004Ford F-150/Expedition 5.4L 2V trucks crack the plastic intake manifold on the driver side around the coolant crossover — Ford TSB 06-26-3 covers the plastic-to-aluminum intake update.
- 1996-2004Ford Mustang GT 4.6L 2V cars suffer driver-side valve cover gasket failure that lets oil onto the exhaust manifold and cooks the upstream Bank 2 sensor.
- 2004-2008F-150 5.4L 3V trucks suffer driver-side spark plug blowout exactly like Bank 1, often setting P1151 with cylinder 5 or 7 misfire codes.
- 1997-2003Ford E-150/E-250 Econoline 4.6L vans crack the rear-of-engine PCV vacuum tee buried under the doghouse, leaning out Bank 2 first.
Estimated repair$25 to $1,400.
Look up another code
More free tools