P0304 on Toyota Corolla E140: Cylinder 4 Misfire Detected

Short answer: P0304 means “Cylinder 4 Misfire Detected”. The car’s computer has found a fault in the Engine system and turns on the Check engine light (MIL). First check: read the code and freeze-frame data with an OBD-II scanner.

Standard OBD-II code Same meaning on all cars (SAE J2012). Not checked against this car’s factory manual.

Code

P0304

System

Engine

Dashboard light

Check engine light (MIL)

Applies to

Generic OBD-II meaning. Not every code is used by this car.

Confidence

medium (generic OBD-II definition, not checked against the factory manual for this car)

Source

obd-codes.com

Symptoms and when it is set

1. Check engine light on
2. The engine may be harder to start
3. The engine may stumble / stumble, and/or hesitate

Likely causes

1. Faulty spark plug or wire
2. Faulty coil (pack)
3. Faulty oxygen sensor(s)
4. Faulty fuel injector
5. Burned exhaust valve
6. Faulty catalytic converter(s)
7. Running out of fuel

What to check, in order

1. Read the code and freeze-frame data with an OBD-II scanner
2. Check the connector and wiring of the part named in the code
3. Test the part with scanner live data or a multimeter, using the values in the repair manual
4. Fix the cause, clear the code and test-drive

Related on this car

• All fault codes for this car
• Warning lights
• Where the parts are (parts map)
• Common problems

Same code on other cars

• P0304 · Toyota Vitz (1st gen)
• P0304 · Toyota Corolla (11th gen, E170)
• P0304 · Honda City (5th gen, GM2)
• P0304 · Honda Civic (10th gen, FC)
• P0304 · Suzuki Wagon R (Pakistan, K10B)
• P0304 on all cars compared

← P0303 P0325 →

Clearing the code does not fix the fault. If it comes back, the problem is still there. For brakes, airbags and steering, see a trained mechanic.