how to fix P0171 and P0174 codes in Honda Civic 9th Generation (2012-2015)

Honda Civic 9th Generation (2012-2015)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0171, P0174

3 min read

574 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 P0171 and P0174 codes in Honda Civic 9th Generation. Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0171, P0174

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
•Decreased fuel efficiency
•Engine misfire during acceleration
•Unusual noises from the engine
•Increased emissions

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0171 and P0174.
2
Inspect the intake system for vacuum leaks, including hoses and gaskets.
3
Check the mass air flow (MAF) sensor for proper operation and cleanliness.
4
Inspect the fuel system, including fuel pressure and filter condition.
5
Test the oxygen sensors for functionality.
6
Examine the throttle body for carbon buildup or obstructions.

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
•Vacuum gauge
•Torx or Phillips screwdriver set
•Fuel pressure gauge
•MAF cleaner spray
•O2 sensor socket

Parts Required

•Vacuum hoses (as needed)
•MAF sensor (if cleaning is ineffective)
•Fuel filter (if clogged)
•Oxygen sensors (if faulty)

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0171 and P0174.
2
Inspect the intake system for vacuum leaks, including hoses and gaskets.
3
Check the mass air flow (MAF) sensor for proper operation and cleanliness.
4
Inspect the fuel system, including fuel pressure and filter condition.
5
Test the oxygen sensors for functionality.
6
Examine the throttle body for carbon buildup or obstructions.

Solution

1. Preparation

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

2. Inspect and Repair Vacuum Leaks

Sub-steps:
- Visually inspect all vacuum hoses for cracks or disconnections and replace any faulty hoses.
- Use a smoke machine or carb cleaner to detect leaks while the engine is running.
- Repair any identified leaks by replacing gaskets or hoses as necessary.

3. Clean or Replace MAF Sensor

Sub-steps:
- Locate the MAF sensor in the intake duct.
- Disconnect the MAF sensor electrical connector.
- Remove the MAF sensor using a Torx or Phillips screwdriver.
- Clean the sensor with MAF cleaner spray and allow it to dry.
- If cleaning does not improve performance, replace the MAF sensor with a new one.

4. Inspect and Test Fuel System

Sub-steps:
- Check the fuel pressure using a fuel pressure gauge while the engine is running; compare the readings to manufacturer specifications.
- Replace the fuel filter if it is clogged or has not been replaced in accordance with maintenance schedules.
- If fuel pressure is low, inspect the fuel pump and fuel injectors for proper operation.

5. Inspect and Replace Oxygen Sensors

Sub-steps:
- Locate the upstream and downstream oxygen sensors on the exhaust system.
- Disconnect the electrical connectors and remove the sensors using an O2 sensor socket.
- Install new oxygen sensors and reconnect the electrical connectors.

6. Reassemble and Test

Sub-steps:
- Reconnect any electrical connectors and hoses that were disconnected during repairs.
- Reconnect the negative battery terminal.
- Start the engine and allow it to reach operating temperature.