how to fix P0301 misfire code on Toyota Highlander Third Generation (2014-2019)

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0301

4 min read

619 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0301 cylinder 1 misfire in Toyota Highlander (2014-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0301

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical components.
•Allow the engine to cool before performing any repairs to prevent burns.

Symptoms

•Check engine light illuminated
•Rough idle or engine stalling
•Decreased acceleration or power
•Increased fuel consumption
•Engine vibration or shaking during operation

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0301 and check for any additional codes.
2
Inspect spark plug in cylinder 1 for wear or damage; replace if necessary.
3
Check the ignition coil for cylinder 1 for proper operation; test with a multimeter.
4
Inspect fuel injector for cylinder 1 for clogs or malfunctions.
5
Perform a compression test on cylinder 1 to check for internal engine issues.
6
Inspect wiring and connectors related to the ignition system and fuel injector for corrosion or damage.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Spark plug socket
•Ratchet
•Torque wrench
•Compression gauge
•Fuel injector removal tool
•Socket set

Parts Required

•Spark plug (specific to Toyota Highlander)
•Ignition coil (if needed)
•Fuel injector (if needed)

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0301 and check for any additional codes.
2
Inspect spark plug in cylinder 1 for wear or damage; replace if necessary.
3
Check the ignition coil for cylinder 1 for proper operation; test with a multimeter.
4
Inspect fuel injector for cylinder 1 for clogs or malfunctions.
5
Perform a compression test on cylinder 1 to check for internal engine issues.
6
Inspect wiring and connectors related to the ignition system and fuel injector for corrosion or damage.

Solution

1. Preparation

Gather tools and parts.
Disconnect the negative battery terminal to prevent electrical shorts.
Allow the engine to cool before starting work.

2. Replace Spark Plug

Tools Required: Spark plug socket, ratchet, torque wrench.
Remove the ignition coil from cylinder 1:
1. Disconnect the electrical connector.
2. Remove the mounting bolts and lift the coil out.
Remove the spark plug:
1. Use the spark plug socket to unscrew the spark plug.
2. Inspect the old spark plug for wear, carbon buildup, or oil fouling.
Install the new spark plug:
1. Hand-tighten the new spark plug into the cylinder head.
2. Use the torque wrench to tighten to the manufacturer's specification (typically around 13-16 lb-ft).
Reinstall the ignition coil and reconnect the electrical connector.

3. Replace Ignition Coil (if necessary)

Tools Required: Ratchet, socket set.
Remove the faulty ignition coil (follow the steps in the previous section).
Install the new ignition coil:
1. Position the new coil in place.
2. Secure it with the mounting bolts and reconnect the electrical connector.

4. Clean or Replace Fuel Injector (if necessary)

Tools Required: Fuel injector removal tool, cleaning kit or replacement injector.
Disconnect the fuel line (be cautious of fuel spills).
Remove the fuel injector using the removal tool.
Clean the injector using a cleaning kit or replace it with a new one.
Reinstall the fuel injector, ensuring proper seating and sealing.

5. Perform Compression Test (if necessary)

Tools Required: Compression gauge.
Remove the spark plug from cylinder 1 and insert the compression gauge.
Crank the engine and record the compression reading.
Compare the reading to manufacturer specifications (typically 120-180 psi). If low, further investigation of engine internals may be necessary.