What does the fault code P031300 for Mercedes-Benz mean?

[OValentina]

Mercedes-Benz fault code P031300 indicates that a combustion misfire was detected when the fuel level signal was activated. Diagnostic fault: The diagnostic found that the engine has fault code P031300, which means a combustion misfire was detected when the fuel level signal was activated. Actions taken: During the test drive, engine shaking was observed, indicating a misfire in cylinder 1. Following the guidance of the fault code, operational tests were performed. The power supply end of the ignition coil for cylinder 1 measured 12 volts, and the ground wire had a resistance of 0.2 ohms to ground, indicating the debugging was complete. An attempt was made to swap the ignition coils and spark plugs of cylinders 1 and 2. The ignition waveform for cylinder 2 then appeared normal, confirming the debugging was successful. Fault resolution: No fault symptoms were found.

[VonStephanie]

Seeing the P031300 fault code on your Mercedes indicates an ignition issue in one of the engine cylinders. Specifically, it points to a misfire in cylinder 13—though the engine doesn’t actually have that many cylinders, likely due to system numbering. The most common culprits are aging ignition coils or carbon buildup on the spark plugs, but clogged fuel injectors or insufficient fuel pump pressure could also be to blame. Symptoms include the engine shaking like a massage chair and sluggish acceleration. My advice? Shut off the engine immediately and check the freeze frame data from the fault code. Prioritize inspecting the ignition coil for cracks or leakage in the affected cylinder, and pull the spark plug to check for excessive gap. Don’t delay repairs—otherwise, the catalytic converter could end up burnt to a crisp. A repair shop can use an oscilloscope to measure the ignition waveform and pinpoint the culprit.

[Ramirez]

I've encountered this P031300 fault code several times when repairing Mercedes-Benz vehicles. Essentially, it indicates a combustion interruption in a specific cylinder. Don't be intimidated by the number 13 - it actually refers to a particular cylinder. For example, in AMG's V8 engines, this code might point to the third cylinder. Common causes fall into three categories: ignition system issues like coil pack breakdown or spark plug carbon buildup; fuel system problems such as poor injector atomization; or mechanical faults like valve leakage. I usually ask the owner to recall recent fuel quality first, as poor gasoline can cause misfires. For diagnosis, reading the misfire count per cylinder with a scanner is most straightforward. When removing the corresponding spark plug, use a flashlight to inspect the cylinder interior - if you see wet oil stains on the piston crown, it indicates injector leakage. These issues aren't particularly expensive to fix - replacing an OEM ignition coil typically costs around 500 yuan.

[MacElijah]

Don't panic if you encounter P031300 in your Mercedes. Simply put, the onboard computer detected that a certain cylinder failed to fire when it should have. Although it shows cylinder 13, it actually refers to a specific position. There are three common causes: weak spark due to worn-out spark plugs, insulation layer corrosion of the ignition coil by oil, or a stuck needle valve in the fuel injector. For emergency troubleshooting, you can try feeling the exhaust pipes during a cold start—if one manifold is noticeably cooler, you've identified the faulty cylinder. However, since the Mercedes engine compartment is compact, it's recommended to visit a shop to read the data stream. With recent rainy weather, damp conditions can easily oxidize the high-voltage pack connectors. When handling, apply some conductive paste to prevent recurrence, and consider replacing the air filter—insufficient air intake can also cause combustion abnormalities.