Engine Misfire Detected on Startup (First 1000 Revolutions)

What it means

The engine computer detected a misfire during the first thousand engine revolutions after starting, roughly the first minute. The causes are usually tied to cold starting, such as weak spark plugs or fuel or water leaking into cylinders while parked, and a cylinder-specific code may appear alongside it.

Related codes: P0300P0314P0335P0340P0087P0117

Symptoms4

• Clear shaking or stumbling in the first seconds after starting that then improves.
• Hard or slow starting, especially after sitting for a long time.
• White smoke or fuel smell from the exhaust at startup.
• Check engine light on.

Possible causes7

• Worn spark plugs or a weak ignition coil that struggles when cold.
• A leaking injector that floods its cylinder while the car is parked.
• Fuel pressure bleeding down while parked from a leaking pump check valve or regulator.
• Wrong coolant temperature sensor reading, so the mixture is wrong for a cold start.
• Coolant leaking into a cylinder from a failed head gasket.
• Carbon deposits on the intake valves of direct-injection engines.
• Weak crankshaft or camshaft position sensor signal during cranking (less common).

How to diagnose6

1. Read all codes; a cylinder-specific code stored with this one points the testing to that cylinder.
2. Inspect the spark plugs, especially for fuel wetting or signs of water and coolant.
3. Watch the coolant level; if it drops with no visible leak, have a combustion leak test done on the cooling system.
4. Measure fuel pressure after shutting the engine off and check whether it drops faster than the manufacturer specification.
5. Compare the coolant temperature sensor reading with the outside temperature after a long rest.
6. Check the crankshaft and camshaft sensor signals during cranking if nothing else is found.

How to fix6

1. Replace the spark plugs or the weak coil.
2. Replace the coolant temperature sensor if its reading is wrong.
3. Replace the leaking injector, or the regulator or pump if the pressure loss comes from them.
4. Clean intake valve deposits on direct-injection engines if they are confirmed.
5. Repair the head gasket if coolant is proven to enter the cylinder.
6. Clear the codes and try several cold starts to confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for spark plugs or a temperature sensor, rises with injectors or a fuel pump, and goes well beyond this range if a head gasket failure is confirmed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions