P0301 means the engine computer has counted repeated misfires isolated to cylinder 1, the first cylinder in the firing order. Combustion in that cylinder is incomplete or absent, so the engine runs rough and loses power. The most common cause by far is a worn cylinder-1 spark plug or a failed ignition coil. A replacement plug costs only 10-40 EUR, so start there before chasing fuel or compression faults.
DTC/P0301·Opel
P0301 on Opel: Causes, Symptoms and Fix Cost
Quick Answer
High SeverityNot safe to driveOpel
P0301 on a Opel means the engine computer has counted repeated misfires isolated to cylinder 1, the first cylinder in the firing order. Combustion in that cylinder is incomplete or absent, so the engine runs rough and loses power. The most common cause by far is a worn cylinder-1 spark plug or a failed ignition coil. A replacement plug costs only 10-40 EUR, so start there before chasing fuel or compression faults.
Repair cost on Opel€38 - €1615
What does P0301 mean on a Opel?
Opel Astra
2009-2024On the 1.4 Turbo (A14NET/B14) the ignition cassette or individual coil over cylinder 1 is a common misfire source, and the plugs are sensitive to the correct heat range and gap. Older 1.6 and 1.8 petrol units can misfire from a tired coil pack or a vacuum leak at the intake gasket near cylinder 1. Parts are inexpensive and most jobs are DIY-friendly.
What causes P0301 on a Opel?
Beyond the generic causes listed on the main P0301 page, these are the Opel-specific patterns we see most often:
Opel AstraCylinder-1 coil or ignition cassette failure on the 1.4 Turbo
Opel AstraIntake-gasket vacuum leak near cylinder 1 on older 1.6/1.8 petrol
How to diagnose P0301 on a Opel with OBD2
Follow these steps to pinpoint the root cause of P0301:
- Read freeze-frame data to capture RPM, engine load, and coolant temperature at the moment the misfire was logged, which narrows cold-start versus load-related faults
- Swap the cylinder-1 ignition coil with the coil from cylinder 2, clear the code, and drive. If the misfire moves to cylinder 2 (now P0302), the coil is the fault
- Remove and inspect the cylinder-1 spark plug for electrode wear, carbon fouling, oil, or an out-of-spec gap. Compare it side by side with a plug from a healthy cylinder
- Confirm the cylinder-1 injector is clicking with a noid light or stethoscope, and check its resistance and wiring connector for an open or corroded pin
- Run a compression test on cylinder 1 and compare to its neighbours. More than a 10 percent drop, or a low reading that rises after adding oil, points to rings or valves
- Smoke-test or spray-test the cylinder-1 intake runner for a vacuum leak, and scan live fuel trims for a lean correction that tracks that cylinder
How much does P0301 cost to fix on a Opel? (EUR)
Estimated repair costs on a Opel (Opel parts and labour typically run 5% below the average for this code).
Prices estimated as of May 2026. Costs vary by region, vehicle, and shop.
Related codes that often appear with P0301 on Opel
These codes commonly cluster with P0301 on Opel vehicles:
FAQ: P0301 on Opel
What does the P0301 code mean?
P0301 means the engine control unit has detected repeated misfires in cylinder 1, the first cylinder in the firing order. The ECU watches tiny crankshaft speed drops on each combustion event, and once cylinder 1 misses enough times within a set window it stores the code. Unlike P0300 (random misfire across several cylinders), P0301 isolates the fault to one cylinder, which makes diagnosis faster.
What are the symptoms of a P0301 misfire?
Common signs are a rough or shaking idle, a rhythmic stumble, vibration felt in the steering wheel or seat, hesitation and lost power on acceleration, higher fuel use, and sometimes a fuel or rotten-egg smell from the exhaust. The check engine light is on, and a flashing light means cylinder 1 is misfiring hard enough to risk the catalytic converter right now.
What causes a P0301 code?
The two most common causes are a worn cylinder-1 spark plug and a failed cylinder-1 ignition coil. After those come a clogged or leaking injector on cylinder 1, a vacuum leak at that intake runner, damaged plug wiring, and, less often, low compression from a burnt valve, worn rings, or a head gasket leak. Because the fault is on one cylinder, start with the cheap ignition parts before opening up the engine.
Is it safe to drive with a P0301 code?
It is not recommended. A persistent cylinder-1 misfire pushes raw fuel into the exhaust, which can overheat and ruin the catalytic converter, a far more expensive repair than a plug or coil. If the check engine light is flashing, pull over and stop driving. If it is steady and the engine still runs, drive only the short distance needed to reach a workshop.
How do you fix and clear a P0301 code?
Fix the root cause first, then clear the code. The fastest test is to swap the cylinder-1 coil with an adjacent cylinder, clear codes, and see if the misfire follows the coil. If it does, replace the coil; if not, fit a new spark plug, then check the injector, wiring, and compression. After the repair, an OBD2 scanner clears the stored code, but it will return if the underlying fault was not fixed.
How much does it cost to fix P0301, and where is cylinder 1?
A spark plug runs about 10-40 EUR and an ignition coil about 40-200 EUR, both quick jobs that are often DIY-friendly. Injector cleaning or replacement is roughly 100-380 EUR, while compression-related valve or head gasket repair can reach several hundred to over a thousand euros. Cylinder 1 is usually at the timing-belt or chain end on inline engines; on V-engines it sits on a specific bank, so check the firing-order label or owner's manual.
Looking for the full P0301 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0301 guideSkanyx · Opel
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