how to fix P0171 and P0174 codes in Honda Accord 9th Generation (2013-2017)

Honda Accord 10th Generation (2018-2022)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0171, P0174

4 min read

617 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 lean fuel mixture issues in Honda Accord (2013-2017). 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 battery before working on electrical systems.
•Relieve fuel system pressure before servicing fuel components.

Symptoms

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

Diagnostic Steps

1
Scan the vehicle's OBD-II system and confirm the presence of codes P0171 and P0174.
2
Inspect the air intake system for vacuum leaks, including hoses and the intake manifold.
3
Check the Mass Air Flow (MAF) sensor for proper function and cleanliness.
4
Inspect the fuel system, including fuel pressure and the fuel filter for clogs.
5
Verify the operation of the fuel injectors.
6
Test the oxygen sensors for proper operation.

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
•Smoke machine
•MAF cleaner
•Fuel pressure gauge
•Injector cleaning kit
•Multimeter
•Torque wrench

Parts Required

•MAF sensor (if needed)
•Fuel filter
•Fuel injectors (if needed)
•Oxygen sensors (if needed)

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Diagnostic Steps

1
Scan the vehicle's OBD-II system and confirm the presence of codes P0171 and P0174.
2
Inspect the air intake system for vacuum leaks, including hoses and the intake manifold.
3
Check the Mass Air Flow (MAF) sensor for proper function and cleanliness.
4
Inspect the fuel system, including fuel pressure and the fuel filter for clogs.
5
Verify the operation of the fuel injectors.
6
Test the oxygen sensors for proper operation.

Solution

1. Preparation

Gather necessary tools and safety equipment.
Disconnect the negative battery terminal to prevent electrical shorts.
Ensure the engine is cool before starting the work.

2. Inspect and Repair Vacuum Leaks

Sub-steps:
1. Visually inspect all vacuum hoses for cracks or disconnections.
2. Use a smoke machine to identify any hidden leaks in the intake system.
3. Replace any damaged hoses or gaskets.
Tools Required: Smoke machine, pliers, assorted vacuum hoses.

3. Clean or Replace the MAF Sensor

Sub-steps:
1. Disconnect the MAF sensor electrical connector.
2. Remove the MAF sensor from the intake duct.
3. Clean the MAF sensor using MAF cleaner spray. Avoid touching the sensor elements.
4. If damaged, replace the MAF sensor with a new one.
5. Reinstall the MAF sensor and reconnect the electrical connector.
Tools Required: MAF cleaner, screwdriver set.

4. Check Fuel System

Sub-steps:
1. Check the fuel pressure using a fuel pressure gauge. It should meet the manufacturer's specifications (usually around 40-50 psi).
2. If low, inspect the fuel pump and replace if necessary.
3. Replace the fuel filter if it is clogged or hasn't been changed in accordance with the maintenance schedule.
Tools Required: Fuel pressure gauge, wrench set, fuel filter.

5. Inspect Fuel Injectors

Sub-steps:
1. Remove the fuel rail to access the fuel injectors.
2. Check for clogs or leaks around the injectors.
3. Clean or replace any faulty injectors.
4. Reassemble the fuel rail and ensure all connections are secure.
Tools Required: Injector cleaning kit or replacement injectors, torque wrench.

6. Test Oxygen Sensors

Sub-steps:
1. Use a multimeter to check the voltage output from the upstream and downstream oxygen sensors.
2. Replace any oxygen sensor showing faulty readings.
3. Reinstall the connectors and ensure proper operation.
Tools Required: Multimeter, oxygen sensor socket.