why does my Ford Explorer Fifth Generation (2011-2019) check engine light come on and off

Ford Explorer Fifth Generation (2011-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0420, P0300

3 min read

564 words

Problem Statement

Learn how to diagnose and fix the intermittent check engine light on a 2011-2019 Ford Explorer. Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0420, P0300

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before opening any components related to the engine or exhaust.

Symptoms

•Check engine light illuminated (intermittently)
•Possible rough idle or stalling
•Decreased fuel efficiency
•Unusual engine noises (knocking or pinging)
•Smell of fuel or exhaust fumes
•Reduced engine performance (loss of power)

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify specific trouble codes.
2
Inspect the gas cap for proper sealing and potential leaks.
3
Check the engine oil and coolant levels to ensure they are within normal ranges.
4
Examine the air filter for clogs or excessive dirt.
5
Inspect ignition components (spark plugs, wires, coils) for wear or damage.
6
Test the battery and alternator voltage to ensure proper electrical supply.

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
•Socket set
•Torque wrench
•Screwdrivers
•Multimeter

Parts Required

•Spark plugs
•Ignition coils (if faulty)
•Air filter
•Oxygen sensors (if faulty)
•Catalytic converter (if damaged)

Related Faults

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify specific trouble codes.
2
Inspect the gas cap for proper sealing and potential leaks.
3
Check the engine oil and coolant levels to ensure they are within normal ranges.
4
Examine the air filter for clogs or excessive dirt.
5
Inspect ignition components (spark plugs, wires, coils) for wear or damage.
6
Test the battery and alternator voltage to ensure proper electrical supply.

Solution

1. Preparation

Gather all necessary tools and parts.
Ensure the vehicle is on a level surface and the engine is cool.
Disconnect the negative battery terminal to prevent accidental electrical shorts.

2. Address Error Codes

Connect the OBD-II scanner and retrieve the error codes.
Research the specific error codes to determine the underlying issue (e.g., P0420 for catalytic converter efficiency, P0300 for random misfire).
Clear the codes and take the vehicle for a test drive to see if the light returns.

3. Replace Faulty Components

Based on the error codes:
- If ignition components are faulty:
  1. Remove the ignition coil(s) and spark plug(s).
  2. Install new spark plugs with a torque specification of 13 lb-ft.
  3. Reinstall the ignition coil(s).
- If the air filter is dirty:
  1. Remove the air filter housing lid.
  2. Replace the old air filter with a new one according to the manufacturer's specifications.
  3. Reassemble the air filter housing.

4. Inspect and Repair Emission Components

For issues related to the catalytic converter or exhaust:
1. Inspect the exhaust system for leaks or damage.
2. If necessary, replace the catalytic converter, ensuring proper alignment and use of new gaskets.
3. Verify that the oxygen sensors are functioning and replace any faulty sensors.

5. Reconnect Battery and Final Checks

Reconnect the negative battery terminal.
Start the engine and check for any new error codes.
Monitor the vehicle for any abnormal behavior before concluding the repair.