Worn or fouled spark plug specific to cylinder 1, with gap or heat range unsuitable for the alternative fuel; Failed ignition coil or spark plug wire on cylinder 1; Clogged or leaking alternative fuel injector on cylinder 1; Low alternative fuel pressure or contaminated alternative fuel; Vacuum leak at the intake port for cylinder 1; Mechanical fault such as low compression, a bad valve, or a failed head gasket on cylinder 1; Corroded or damaged wiring to the cylinder 1 injector or ignition coil

DTC codes / P2Exx · Hybrid propulsion / P2E59

P2E59Cylinder 1 Alternative Fuel Misfire Detected

Q: What does code P2E59 mean?

Cylinder 1 Alternative Fuel Misfire Detected. P2E59 means the engine computer has detected a misfire on cylinder 1 while the engine is running on its alternative fuel, such as compressed natural gas, propane, or E85. The computer monitors crankshaft speed fluctuations and flags this code when cylinder 1's contribution to power drops beyond an acceptable threshold specifically during alternative-fuel operation.

P2E59 means the engine computer has detected a misfire on cylinder 1 while the engine is running on its alternative fuel, such as compressed natural gas, propane, or E85. The computer monitors crankshaft speed fluctuations and flags this code when cylinder 1's contribution to power drops beyond an acceptable threshold specifically during alternative-fuel operation.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Check engine light illuminated, 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 on the alternative fuel source
A fuel smell or sulfur odor from the exhaust in some cases
Often no symptoms besides the warning light when the misfire is intermittent

Common causes, most likely first

Worn or fouled spark plug specific to cylinder 1, with gap or heat range unsuitable for the alternative fuel
Failed ignition coil or spark plug wire on cylinder 1
Clogged or leaking alternative fuel injector on cylinder 1
Low alternative fuel pressure or contaminated alternative fuel
Vacuum leak at the intake port for cylinder 1
Mechanical fault such as low compression, a bad valve, or a failed head gasket on cylinder 1
Corroded or damaged wiring to the cylinder 1 injector or ignition coil

How to diagnose and fix it

Scan all stored codes and freeze-frame data to confirm the misfire is isolated to cylinder 1 and occurs only in alternative-fuel mode
Inspect the spark plug on cylinder 1 for fouling, wear, or incorrect gap, and replace it if needed
Swap the ignition coil from cylinder 1 with a known-good cylinder and see if the misfire follows the coil
Check the alternative fuel injector on cylinder 1 for clogging, leaks, or electrical resistance out of specification
Perform a compression test and cylinder leak-down test on cylinder 1 to rule out mechanical faults
Smoke-test the intake system for vacuum leaks at the cylinder 1 port
Verify alternative fuel pressure and quality, and inspect the fuel supply components for contamination

Why alternative-fuel misfires fool good technicians

A P2E59 can set even when the engine runs perfectly on gasoline, because the alternative fuel's higher octane or different burn characteristics expose weak ignition components that gasoline masks.
Technicians often replace all spark plugs and coils without isolating cylinder 1, but the code specifically flags that cylinder, so swapping components one at a time is the faster diagnostic path.
Alternative fuel injectors are prone to clogging from fuel impurities and can fail gradually, so a flow test or injector balance test is more revealing than a simple resistance check.
A vacuum leak at the intake manifold gasket near cylinder 1 can cause a lean misfire only under alternative-fuel operation because the fuel trim strategy differs between fuels.
The code does not always mean the alternative fuel system is at fault; a marginal ignition component or mechanical issue on cylinder 1 can trigger it when the engine switches to the alternative fuel map.

Can I keep driving with P2E59?

You can drive the vehicle short distances to a repair shop, but avoid heavy acceleration and sustained high-speed driving because a persistent misfire can overheat the catalytic converter. If the check engine light is flashing, stop driving and have the vehicle towed.

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.