2018 Mercedes-Benz P0304: What It Means & Is It Safe to Drive?
P0304 on the 2018 Mercedes-Benz: Cylinder 4 Misfire Detected. Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
What this code means
Misfire confirmed on cylinder 4. On 4-cylinder engines, this is the last cylinder—check coil and plug first, then injector, then compression.
Common causes on the 2018 Mercedes-Benz
- Worn spark plug on cylinder 4
- Failed ignition coil on cylinder 4
- Faulty or clogged fuel injector
- Low compression or valve issue
Symptoms
- Check Engine Light
- Rough idle and shaking
- Poor acceleration or power loss
Typical fixes
- Replace spark plug and COP coil on cylinder 4
- Clean or replace fuel injector
- Compression and leak-down test if basic parts check out
Repair cost range
For a 2018 Mercedes-Benz, repairs for P0304 typically fall between $150 and $900, depending on the root cause and labor rates in your area.
Known issues on Mercedes-Benz
Mercedes M271 turbocharged four-cylinder P0304 typically indicates a failed ignition coil or worn spark plug. The M271 uses a coil-over-plug design and coil failures are not uncommon past 80k miles. On M272 V6, balance shaft gear inspection applies before coil diagnosis.
Most commonly affected models