What is a misfire?
A misfire means one or more cylinders isn’t burning fuel correctly. That can be caused by ignition problems (petrol), fuel delivery issues, air leaks, sensor faults, or mechanical issues.
Most common causes we see
⚡ Ignition coil / spark plugs
Most common on petrol engines. Causes shaking, loss of power and engine light.
⛽ Injector / fuel issue
Restricted injector, low fuel pressure, or fuel delivery faults can cause misfires.
💨 Air leak / vacuum leak
Split hose or intake leak can cause lean running and misfires.
🧠 Sensor faults
MAF/MAP, O2 sensors, crank/cam sensors can cause rough running.
🌫 EGR / DPF related
Some diesel faults can feel like misfires or cause severe hesitation.
🔧 Mechanical issues
Less common, but compression problems can cause persistent misfires.
Is it safe to drive?
- Flashing engine light: don’t drive — get help.
- Shaking badly / loss of power: stop driving when safe.
- Mild vibration: drive gently to a safe place and book diagnostics ASAP.
How AutoAid diagnoses a misfire
We scan fault codes, check live data, and test the likely causes (coils, plugs, sensors, air leaks) to confirm the real issue. No parts darts — we find the cause first, then quote.
Want it checked today?
WhatsApp your reg, postcode and when the shaking happens.