Honda Odyssey Replace Mass Air Flow (MAF) Sensor To Fix DTC P0171

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Purpose

This article outlines the procedures to diagnose and confirm Diagnostic Trouble Code (DTC) P0171 on a 2014 – 2019 Honda Odyssey 3.5L, and replace the Mass Air Flow (MAF) sensor to resolve this issue.

Introduction

In cases where the Malfunction Indicator Lamp (MIL) on your vehicle’s dashboard and the Engine Control Module (ECM) has stored DTC P0171, it is necessary to examine the fuel and emission control system, as well as conduct tests on the MAF sensor and oxygen sensors.

P0171: Fuel System Too Lean (Bank 1) - This means that the ECM has detected a lean air-fuel mixture on Bank 1. The 'lean' condition indicates an imbalance in the air-fuel ratio, which means either too much oxygen or too little fuel in the exhaust. Bank 1 refers to the side of the engine that has cylinder 1.

Symptoms of DTC P0171 include:

• MIL ON or flashing
• Reduced engine power and performance
• Engine rough at idle
• Poor fuel economy
• Failed emission test

Possible causes of DTC P0171 are:

• Faulty or damaged MAF sensor
• Vacuum leak(s)
• Damaged intake air duct
• Faulty Oxygen (O2) Sensor
• Faulty or leaking Fuel Injector

If DTC P0171 is present on a 2014 – 2019 Honda Odyssey 3.5L, replacing the MAF sensor may correct the fault.

(This image is for illustrative purposes only and may not match the actual part number)

Inspection and Diagnosis

Step 1: Initial Inspection

During initial inspection, check for obvious signs of mechanical damage, such as:

• torn inlet boots
• missing or broken vacuum tees
• cracked, broken, or disconnected wire harnesses.

Make sure all harness connectors are securely attached and are properly placed in holders. This will prevent potential open or short-circuit issues. Also, check the connectors for corrosion, frayed wiring, and damaged terminals.

Inspect the battery terminals and check battery state of charge before attempting to diagnose possible electrical faults.

Inspect vacuum hoses and ensure they are securely connected to a manifold vacuum source on the engine.

Inspect the air inlet pipes/hoses between the MAF and the throttle body. DTC P0171 may be caused by a vacuum leak, or by a dirty or disconnected MAF sensor. Refer to the Vehicle Emissions Warranty Manual for time and mileage coverage for emissions-related fault(s). For additional information, refer to the Service Manual or applicable Technical Service Bulletin (TSB) prior to continuing.

Step 2: Diagnostic Procedures

1. Fuel Trim value at idle can be greatly affected by vacuum leaks. Check Long-Term Fuel Trim (LTFT) at idle and at 2500 RPM. The value should not exceed +/- 10%.
- If LTFT is within acceptable limits, proceed to Step 2.
- If LTFT is greater than 10% idle but less than 10% at 2500 RPM, a vacuum leak may be present.
- If LTFT is greater than +10% on one bank and -10% on the other bank, check for restricted exhaust or internal mechanical engine problems.

2. Check the MAF sensor readings at 2500 RPM. The MAF value should be approximately 13.3 – 16.3 g/s.
- If values are within specification, inspect for other possible causes such as a vacuum leak, or a faulty fuel injector or oxygen sensor.
- If values are out of specification, replace the MAF sensor and validate the repair.

Replace the MAF sensor

Removal the MAF Sensor

Removal

Step 1 –Disconnect the harness connector (1) from the MAF sensor.

Step 2 – Remove two screws (2).

Step 3 – Remove the MAF sensor (3) and O-ring. Discard the O-ring.

Installation

Installation is accomplished in the reverse order of removal, with the following notes:

• When replacing the MAP sensor, install a new O-ring.
• Tighten screws (2) to 1.5 N-m (0.15 kgf-m, 1.1 lbf-ft)

Validate the Repair

1. Erase DTC(s) and Freeze Frame (FF) information.

2. Confirm the repair using one of the following procedures:

• Conduct Key ON Engine Off (KOEO) and Key ON Engine Running (KOER) tests.
• Perform the OBD2 drive cycle requirements for the fault area.
• Optionally, operate the vehicle within the conditions recorded in the Freeze Frame data for the fault area.

3. Check for pending or stored DTCs. If none are found, the repair is complete.

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