Worn or fouled spark plug specific to cylinder 7, with gap or heat range incorrect for alternative fuel use; Faulty ignition coil or plug wire on cylinder 7 causing a weak or intermittent spark; Clogged or leaking alternative fuel injector on cylinder 7, leading to incorrect fuel delivery; Low compression on cylinder 7 from worn rings, valve issues, or a head gasket problem; Vacuum leak or intake manifold gasket failure near cylinder 7 affecting that cylinder's air charge; Contaminated alternative fuel or incorrect fuel pressure causing lean misfire under load; Wiring or connector fault in the cylinder 7 injector or ignition circuit

DTC codes / P2Exx · Hybrid propulsion / P2E5F

P2E5FCylinder 7 Alternative Fuel Misfire Detected

Q: What does code P2E5F mean?

Cylinder 7 Alternative Fuel Misfire Detected. P2E5F indicates that the engine control module has detected a misfire on cylinder 7 while the engine is operating on an alternative fuel such as compressed natural gas, propane, or E85. The module monitors crankshaft speed fluctuations and identifies that cylinder 7 is not contributing power evenly, which can be caused by ignition, fuel delivery, or mechanical faults specific to that cylinder.

P2E5F indicates that the engine control module has detected a misfire on cylinder 7 while the engine is operating on an alternative fuel such as compressed natural gas, propane, or E85. The module monitors crankshaft speed fluctuations and identifies that cylinder 7 is not contributing power evenly, which can be caused by ignition, fuel delivery, or mechanical faults specific to that cylinder.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illuminated check engine light, often flashing if the misfire is severe
Noticeable engine shake or rough idle, especially when running on the alternative fuel
Reduced power and sluggish acceleration under load
Poor fuel economy or increased alternative fuel consumption
Often no symptoms besides the warning light during light-load driving

Common causes, most likely first

Worn or fouled spark plug specific to cylinder 7, with gap or heat range incorrect for alternative fuel use
Faulty ignition coil or plug wire on cylinder 7 causing a weak or intermittent spark
Clogged or leaking alternative fuel injector on cylinder 7, leading to incorrect fuel delivery
Low compression on cylinder 7 from worn rings, valve issues, or a head gasket problem
Vacuum leak or intake manifold gasket failure near cylinder 7 affecting that cylinder's air charge
Contaminated alternative fuel or incorrect fuel pressure causing lean misfire under load
Wiring or connector fault in the cylinder 7 injector or ignition circuit

How to diagnose and fix it

Scan all stored and pending codes, then check freeze-frame data to confirm the misfire occurs only on alternative fuel
Inspect the spark plug on cylinder 7 for wear, fouling, or incorrect gap, and replace if necessary
Swap the ignition coil from cylinder 7 with a known-good cylinder to see if the misfire moves
Perform a compression test and cylinder leak-down test on cylinder 7 to rule out mechanical faults
Check the alternative fuel injector on cylinder 7 for clogging or leaks, and test its electrical circuit
Smoke-test the intake system for vacuum leaks near cylinder 7
Verify alternative fuel pressure and quality, and recheck misfire counters after repairs

Alternative fuel misfire traps to avoid

A P2E5F can be set by a misfire that only occurs when the engine switches to alternative fuel, so always test-drive with the fuel selector in that mode and monitor misfire counters live.
Technicians often replace the spark plug and coil on cylinder 7 only to find the real cause is a clogged alternative fuel injector that leans out that cylinder under load.
Because alternative fuels burn hotter and drier than gasoline, valve seat recession and spark plug wear can appear on a single cylinder first, so a compression test is essential before parts swapping.
The code does not always mean the cylinder is mechanically failing; a loose intake manifold bolt or a cracked vacuum hose near cylinder 7 can create a lean misfire that mimics a bad injector.
Misfire counters can be triggered by a faulty crankshaft position sensor or reluctor wheel, so check for erratic RPM signals if the misfire seems random across cylinders.

Can I keep driving with P2E5F?

Avoid heavy acceleration and towing until the misfire is repaired, because unburned fuel can overheat and damage the catalytic converter. If the check engine light is flashing, stop driving and have the vehicle towed to prevent converter damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.