Global Fault Code
Free · no signupP0300
Engine shaking/shuddering; Flashing Check Engine Light; Poor fuel economy; Rotten egg smell (catalyst stress).
System
Not specified
Symptom
Engine shaking/shuddering; Flashing Check Engine Light; Poor fuel economy; Rotten egg smell (catalyst stress).
Diagnosis & fix steps
Random or Multiple Cylinder Misfire Detected.
LOGIC: The Crankshaft Position Sensor detects a decrease in RPM during power strokes, indicating incomplete combustion.
ACTION: 1. Check for vacuum leaks.
2. Inspect spark plug condition.
3. Test fuel pressure.
FIX: Replace spark plugs/coils; repair vacuum leaks; clean fuel injectors.
Red Seal field insights
A flashing MIL (Check Engine Light) means the misfire is severe enough to damage your catalytic converter. Do not continue driving or you will turn a $100 fix into a $1,500 one.
Same code keeps coming back?
That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.
Read before you touch anything
- This is general reference information, not a repair manual. It is for trained, qualified technicians.
- Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
- Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
- You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
- Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.
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