how to troubleshoot my Honda Civic 10th Generation (2016-2021) that has a P0138 code

Honda Civic 10th Generation (2016-2021)

Error Codes

1-3 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0138

3 min read

509 words

Problem Statement

Learn how to troubleshoot and fix P0138 high voltage issue in Honda Civic 10th Generation. Step-by-step guide with diagnostic and repair instructions.

Error Code

P0138

Affected Component

Exhaust System

Estimated Time

1-3 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before working on the exhaust system.

Symptoms

•Check engine light illuminated
•Poor fuel economy
•Engine stalling or hesitation during acceleration
•Rough idle
•Increased emissions

Diagnostic Steps

1
Scan the vehicle using an OBD-II scanner to confirm the P0138 code and check for any additional codes that may be present.
2
Inspect the oxygen sensor wiring and connectors for any signs of damage, corrosion, or loose connections.
3
Measure the voltage output of the upstream oxygen sensor with a multimeter while the engine is running.
4
Check the engine's fuel trim readings using the OBD-II scanner to determine if they are outside normal parameters.
5
Verify the vehicle’s ground connections and battery voltage to ensure the electrical system is functioning properly.
6
Inspect the exhaust system for leaks, which could affect the oxygen sensor's readings.

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
•Oxygen sensor socket
•Wrench set
•Torque wrench

Parts Required

•Upstream oxygen sensor (specific to Honda Civic 10th Generation)

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Diagnostic Steps

1
Scan the vehicle using an OBD-II scanner to confirm the P0138 code and check for any additional codes that may be present.
2
Inspect the oxygen sensor wiring and connectors for any signs of damage, corrosion, or loose connections.
3
Measure the voltage output of the upstream oxygen sensor with a multimeter while the engine is running.
4
Check the engine's fuel trim readings using the OBD-II scanner to determine if they are outside normal parameters.
5
Verify the vehicle’s ground connections and battery voltage to ensure the electrical system is functioning properly.
6
Inspect the exhaust system for leaks, which could affect the oxygen sensor's readings.

Solution

1. Preparation

Gather tools and parts required for the repair.
Ensure the vehicle is parked on a flat surface and the engine is cool.
Disconnect the negative battery terminal for safety.

2. Inspect and Repair Wiring

Remove the engine cover if necessary to gain access to the harness.
Visually inspect the wiring and connectors of the upstream oxygen sensor.
If damaged, repair or replace any faulty wiring or connectors.

3. Replace the Upstream Oxygen Sensor

Locate the upstream oxygen sensor (typically near the exhaust manifold).
Use an O2 sensor socket to remove the old sensor by turning it counter-clockwise.
Apply anti-seize compound to the threads of the new sensor (if recommended).
Install the new oxygen sensor by threading it in clockwise and tightening it to the manufacturer’s specifications (typically 30-40 ft-lbs).
Reconnect the electrical connector to the oxygen sensor.

4. Clear the Error Codes

Reconnect the negative battery terminal.
Use the OBD-II scanner to clear the P0138 code from the vehicle’s computer.

5. Test Drive

Start the engine and allow it to idle for a few minutes.
Take the vehicle for a test drive, monitoring for any check engine light illumination.