how to fix P0171 and P0174 codes on Honda Civic 11th Generation (2022-Present)

Honda Accord 11th Gen (2023-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0171, P0174

4 min read

663 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 11th Generation. Step-by-step guide with symptoms, diagnostic steps, 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 systems.
•Allow the engine to cool before performing repairs.

Symptoms

•Check engine light illuminated
•Rough idle or fluctuating RPMs
•Decreased engine performance or acceleration
•Poor fuel economy
•Unusual engine noises (such as hissing)
•Possible stalling during low-speed maneuvers

Diagnostic Steps

1
Scan the vehicle's OBD-II system to confirm the presence of P0171 and P0174 codes.
2
Inspect the air intake system for leaks, loose hoses, or cracked components.
3
Check the mass air flow (MAF) sensor for proper function and cleanliness.
4
Verify fuel pressure using a fuel pressure gauge to ensure it meets specifications.
5
Inspect the fuel injector operation and inspect for clogs or leaking injectors.
6
Check for vacuum leaks around the intake manifold and associated gaskets.

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
•Screwdrivers
•MAF sensor cleaner
•Torx screwdriver
•Fuel pressure gauge
•Torque wrench
•Smoke machine or carburetor cleaner
•Gasket scraper

Parts Required

•MAF sensor (if found defective)
•Fuel injectors (if clogged or leaking)
•Fuel filter (if pressure is low)
•Intake gaskets (if leaks are detected)

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Diagnostic Steps

1
Scan the vehicle's OBD-II system to confirm the presence of P0171 and P0174 codes.
2
Inspect the air intake system for leaks, loose hoses, or cracked components.
3
Check the mass air flow (MAF) sensor for proper function and cleanliness.
4
Verify fuel pressure using a fuel pressure gauge to ensure it meets specifications.
5
Inspect the fuel injector operation and inspect for clogs or leaking injectors.
6
Check for vacuum leaks around the intake manifold and associated gaskets.

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the engine is cool and the vehicle is in a safe working area.
Disconnect the battery to prevent electrical shorts during repairs.

2. Inspect Air Intake System

Sub-steps:
- Remove the air intake duct to access the throttle body and MAF sensor.
- Visually inspect the duct for cracks or loose connections.
- If any damage is found, replace the affected components.
Tools Required:
- Socket set
- Screwdrivers

3. Clean or Replace MAF Sensor

Sub-steps:
- Disconnect the electrical connector from the MAF sensor.
- Remove the MAF sensor from the air intake housing.
- Clean the MAF sensor using MAF cleaner spray. Do not touch the sensor with fingers or tools.
- Allow the sensor to dry and reinstall it.
Tools Required:
- MAF sensor cleaner
- Torx screwdriver

4. Check Fuel Pressure

Sub-steps:
- Connect a fuel pressure gauge to the fuel rail Schrader valve.
- Turn the ignition to the "ON" position (without starting the engine) to check the pressure reading.
- Compare the reading to the manufacturer's specifications (usually around 40-50 psi). If low, check the fuel pump and fuel filter.
Tools Required:
- Fuel pressure gauge

5. Inspect Fuel Injectors

Sub-steps:
- Disconnect the electrical connectors from the fuel injectors.
- Remove the fuel rail to access the injectors.
- Inspect for leaks or clogs in the injectors; clean or replace if necessary.
- Reinstall the fuel rail and reconnect the electrical connectors.
Tools Required:
- Socket set
- Torque wrench (for fuel rail bolts)

6. Check for Vacuum Leaks

Sub-steps:
- Use a smoke machine or carburetor cleaner to identify vacuum leaks around the intake manifold and gaskets.
- Inspect the gaskets for any signs of wear or damage and replace as necessary.
Tools Required:
- Smoke machine or carburetor cleaner
- Gasket scraper (if replacing gaskets)