how to fix P0138 code in Honda CR-V Fifth Generation (2017-2022)

Honda CR-V 6th Gen (2023-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0138

3 min read

544 words

Problem Statement

Learn how to diagnose and fix P0138 high voltage O2 sensor issue in Honda CR-V (2017-2022). Step-by-step guide with diagnostic and repair instructions.

Error Code

P0138

Affected Component

Exhaust System

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 exhaust system.

Symptoms

•Check engine light illuminated
•Poor fuel economy
•Rough engine idle
•Increased emissions
•Failed emissions test

Diagnostic Steps

1
Scan the vehicle's OBD-II system to confirm the P0138 code and check for any additional codes.
2
Inspect the wiring and connectors leading to the upstream O2 sensor for signs of damage, corrosion, or loose connections.
3
Measure the voltage output from the upstream O2 sensor using a multimeter.
4
Check the O2 sensor heater circuit for continuity and proper functioning.
5
Inspect the engine coolant temperature sensor to ensure it is functioning correctly, as it can affect O2 sensor readings.
6
Clear the fault codes and perform a test drive to see if the P0138 code returns.

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
•Multimeter
•O2 sensor socket
•Ratchet
•Torque wrench
•Wire strippers
•Electrical tape

Parts Required

•Upstream O2 sensor
•Electrical connectors

Related Faults

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Diagnostic Steps

1
Scan the vehicle's OBD-II system to confirm the P0138 code and check for any additional codes.
2
Inspect the wiring and connectors leading to the upstream O2 sensor for signs of damage, corrosion, or loose connections.
3
Measure the voltage output from the upstream O2 sensor using a multimeter.
4
Check the O2 sensor heater circuit for continuity and proper functioning.
5
Inspect the engine coolant temperature sensor to ensure it is functioning correctly, as it can affect O2 sensor readings.
6
Clear the fault codes and perform a test drive to see if the P0138 code returns.

Solution

1. Preparation

Gather tools and parts required for the repair.
Disconnect the negative battery terminal to avoid electrical shorts.
Allow the engine to cool completely before starting any repair work.

2. Inspect and Repair Wiring

Tools Required: Multimeter, wire strippers, electrical tape
Check the wiring harness and connectors leading to the O2 sensor for any visible damage or corrosion.
If damaged, repair the wiring using appropriate wire connectors and electrical tape to insulate exposed areas.

3. Replace Upstream O2 Sensor

Tools Required: O2 sensor socket, ratchet, torque wrench
Locate the upstream O2 sensor, which is typically found before the catalytic converter on the exhaust manifold.
Use an O2 sensor socket and ratchet to unscrew the old sensor from its location.
Apply anti-seize compound to the threads of the new O2 sensor to prevent seizing.
Install the new O2 sensor and torque it to the manufacturer’s specifications (usually around 30 lb-ft).
Reconnect the electrical connector to the new O2 sensor.

4. Reconnect Battery and Test

Reconnect the negative battery terminal.
Start the engine and let it reach operating temperature.
Monitor the O2 sensor voltage using the multimeter to ensure it fluctuates between 0.1V and 0.9V during operation.