The P0301 code indicates that one or more engine cylinders are misfiring. The last digit of the code indicates the cylinder number in which the misfiring is detected. This code creates a risk to the vehicle’s drivability and is therefore considered serious.
Causes of occurrence
The usual cause of the P0301 error code on Toyota vehicles is the failure of the coils and spark plugs. Other prerequisites may be:
- air leak in the fuel system;
- damage to the ignition coil winding;
- soot accumulation on fuel injectors;
- Incorrect adjustment of the engine intake and exhaust valves.
When the spark plugs are operating, a micro-explosion ignites the fuel-air mixture in each cylinder. Misfires contribute to a decrease in the number of crankshaft revolutions, which leads to a loss of power in the power unit.
Methods of elimination P0301 error code
To find out the reasons for the error, first of all, you need to check the condition of the high-voltage wires and ignition coils. You need to look for breaks and damage to the insulation. It would not be superfluous to connect a multimeter: perhaps one of the coils simply burned out. The same tester can also be used to check the ignition module. Defective parts must be replaced immediately.
Next, you can measure the compression in all cylinders and unscrew and inspect the spark plugs one by one. If there is black carbon on the spark plug, this is the cause of misfires.
Fuel injector diagnostics are essential and require specialized equipment such as diagnostic scanners and flow testing tools, available at certified auto service centers.
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