What does it mean?
P1348 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Random/Multiple Misfire Detected . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms
- Check engine light flashing while the misfire is active, then staying on afterwards
- Vibration at idle and a noticeable stumble when the engine is under light load
- Loss of acceleration and a flat feeling when pulling away or climbing
- Rough cold start with the roughness easing as the engine warms
- Higher fuel consumption and, in some cases, a strong exhaust smell
Likely causes
- Unmetered air entering through a torn intake boot, a leaking manifold gasket or a disconnected vacuum line
- Insufficient fuel supply from a tired pump, restricted filter or a partly blocked fuel strainer
- Spark plugs at the end of their service life across the whole engine
- Contaminated or water-affected fuel in the tank
- Faulty mass air flow or manifold pressure sensor giving the module a wrong load value, which upsets the mixture on every cylinder
- Exhaust restriction from a collapsed catalytic converter raising back pressure
- Cam timing slightly out because of chain wear, weakening combustion on all cylinders
How to fix it
- Retrieve the freeze frame and note whether the misfire happens cold, at idle or only under load, which narrows the search quickly
- Review fuel trims and the mass air flow or manifold pressure reading against expected values for the engine
- Smoke test the intake system and inspect all vacuum connections and the crankcase ventilation circuit
- Measure fuel pressure at idle and under load, and check the filter and pump delivery if pressure drops off
- Remove and read the spark plugs, replacing the full set if they are worn or fouled, and evaluate coil condition
- Check exhaust back pressure if the engine feels choked at higher rpm
- If nothing electrical or fuel-related is found, verify cam timing and perform compression testing to expose mechanical wear