What does code P0300 mean on a Mercedes-Benz and is it safe to drive?
P0300: Random/Multiple Cylinder Misfire Detected. Here's what it means on your Mercedes-Benz, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
What this code means
The PCM has detected misfires across multiple cylinders. This can cause damage to the catalytic converter if driven for long.
Common causes for your Mercedes-Benz
- Worn spark plugs or ignition coils
- Clogged or bad fuel injectors
- Low compression
- Vacuum leak, bad MAF, or fuel delivery issue
Symptoms
- Check Engine Light (often flashing under load)
- Rough idle, shaking, loss of power
- Possible smell of unburned fuel
Typical fixes
- Replace spark plugs and coils as needed
- Clean or replace fuel injectors
- Fix vacuum/fuel issues
- Compression test if no obvious cause
Repair cost range
For a Mercedes-Benz, repairs for P0300 often fall between $150 and $1200, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Mercedes-Benz
Mercedes P0300 on M272 3.5L V6 engines is often caused by the balance shaft gear tooth fracture—a known issue where the plastic-toothed idler gear in the timing system cracks and causes cam timing walk, resulting in P0300 and a rattling noise on startup. This requires immediate attention as timing failure can cause engine damage. On M276 V6 and M278 V8 engines, individual coil-on-plug boots crack with age. On CDI diesel engines, P0300 indicates glow plug failure or a fuel injector return leak—a completely different failure path.
Most commonly affected models