OBD-II Code
P0296
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)
$180–$2,400
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P0296 means cylinder 12 specifically is contributing less power than the other cylinders — the ECM measures crankshaft acceleration per cylinder firing event over a rolling window (typically 1,000 revolutions) and flags any cylinder whose contribution falls below the expected percentage of total torque (usually 70-85% of cylinder average, depending on manufacturer).
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 procedureP0296 means cylinder 12 specifically is contributing less power than the other cylinders — the ECM measures crankshaft acceleration per cylinder firi…
P0296 means cylinder 12 specifically is contributing less power than the other cylinders — the ECM measures crankshaft acceleration per cylinder firing event over a rolling window (typically 1,000 revolutions) and flags any cylinder whose contribution falls below the expected percentage of total torque (usually 70-85% of cylinder average, depending on manufacturer). This is a contribution code, not necessarily a misfire code, so it can set BEFORE the misfire counter exceeds the threshold — meaning the cylinder is firing but weakly, not skipping outright.
Cheapest-first ladder
- confirm the vehicle is actually a V12 (cylinder 12 only exists on true V12s), then identify cylinder 12 on the FSM cylinder-layout diagram (typically the rear-most cylinder on one bank), pull the coil and plug from cylinder 12, read the plug for fouling/oil/fuel-wet condition, swap the coil with an adjacent cylinder's coil and clear the code.
- If the contribution fault moves to the adjacent cylinder, the coil is bad; if it stays on 12, swap plugs next.
- If both swaps fail to move the fault, measure injector resistance at the cylinder 12 injector — a healthy port-fuel injector reads 12-16 ohms, and a healthy direct-injection injector reads 1-2 ohms; a drifting injector that flows 10-20% less fuel will set P0296 without setting a hard misfire code.
- Compression test cylinder 12 if injector and ignition check out — anything under 85% of the highest-reading cylinder is a mechanical fault.
- The expensive misdiagnosis on P0296: techs immediately reach for a coil pack on a V12, but on most V12 platforms the cylinder 12 plug is buried under the intake plenum or a covered firewall location, and the actual cause is usually a coil that's been weakened by heat soak from sitting at the back of the engine bay for years — replace the coil AND consider replacing the coil for the symmetrically opposite cylinder (cylinder 6 on most V12 firing orders), since it lives in the same heat environment.
Vehicle-specific patternsV12 engines are the only platforms that throw P0296, and the list is short.
V12 engines are the only platforms that throw P0296, and the list is short. BMW N73 6.0L V12 (2003-2008 760i, 760Li) and N74 6.0L twin-turbo V12 (2009-2015 760i, Rolls-Royce Ghost/Phantom/Wraith/Dawn) is the most common P0296 vehicle — the rear-bank cylinders 7-12 are buried under the intake plenum and the coil at cylinder 12 sees the worst heat soak from the firewall; coil failure at 60-100k is the norm. Mercedes-Benz M275 6.0L twin-turbo V12 (2003-2014 S65 AMG, CL65 AMG, SL65 AMG, Maybach 57S/62S) throws P0296 commonly from injector flow degradation on the rear-bank cylinders — the M275 is sensitive to injector matching and a single drifting injector sets the contribution code before a misfire. Mercedes M279 6.0L V12 (2013+ S65 AMG, S600) is the M275 successor and inherits the same pattern. Aston Martin V12 (5.9L and 6.0L in DB9, DBS, Vanquish, Rapide) shares Ford-derived coil designs and throws P0296 from coil failures on cylinder 12 specifically because of the rear-firewall heat soak. Note that VW W12 (Phaeton, Bentley Continental GT) and Audi A8 W12 use a W12 layout not a true V12 and number cylinders differently — P0296 on those platforms refers to a different physical cylinder location per the W-engine firing order; verify cylinder identity on FSM before tooling.
Estimated repair$180 to $2,400.
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