2017-2019 Honda Pilot ECM: Programming and Part Matching Guide

Symptoms of a Failing 2017-2019 Honda Pilot ECM

A faulty ECM can cause a wide range of problems, from a simple check engine light to a vehicle that won't start at all. Because the ECM controls so many different systems, symptoms can sometimes be mistaken for other issues. It's important to perform a full diagnosis to rule out simpler problems like bad sensors or wiring before condemning the ECM.

• Check Engine Light: This is often the first and most obvious sign. An ECM-specific trouble code may be stored, or the ECM might set codes for sensors that are actually working correctly.
• Engine Stalling or Misfiring: The engine may stall unexpectedly, run rough, or misfire. This can happen intermittently and without a clear pattern.
• No-Start Condition: You may find the engine cranks over but refuses to start. This happens 🎬 Watch: Troubleshooting a Honda Pilot that won't start because the ECM is not providing the correct commands for fuel and spark.
• Poor Engine Performance: A failing ECM can lead to a noticeable loss of power, sluggish acceleration, and a decrease in fuel economy as it struggles to manage the engine's air-fuel mixture and timing.
• Shifting Problems: The ECM communicates with the transmission control module. Faulty data from the ECM can lead to hard or delayed shifting.

Common Diagnostic Trouble Codes (DTCs)

While many codes can indicate an ECM issue, codes specifically pointing to an internal processor failure are a strong indicator. These can include:

• P0600 - P0605: This range of codes generally indicates internal communication or memory errors within the control module itself.
• P0685: This code points to a fault in the ECM/PCM power relay control circuit.

Known Issues, Recalls, and Technical Service Bulletins (TSBs)

While there are no specific recalls for the ECM itself, there are important service bulletins and investigations for this Pilot generation that owners should be aware of.

TSB 21-010: False Catalyst & Misfire Codes

Honda issued a Technical Service Bulletin for 2017-2019 Pilots regarding the check engine light illuminating with certain codes. The PCM software may misinterpret sensor data and incorrectly flag the catalytic converter or detect misfires.

• Affected Codes: P0420, P0430 (Catalyst Efficiency), P0300-P0306 (Misfires), P219A, P219B (Air-Fuel Ratio Variation).
• Solution: The fix involves a software update and, in some cases, replacing the fuel injectors. American Honda extended the warranty for these specific repairs to 10 years or 150,000 miles.
• Why it Matters: These symptoms could easily be misdiagnosed as a complete ECM failure. It is crucial to check if this TSB applies to your vehicle before replacing the module.

NHTSA Engine Failure Investigation

The National Highway Traffic Safety Administration (NHTSA) has an open investigation (PE25008) into a significant number of engine failures on 2016-2020 Honda Pilots. This issue is related to a mechanical failure of the connecting rod bearings and is NOT an ECM problem. However, a catastrophic engine failure will also result in a no-start condition, so it's a known issue for the vehicle platform.

Buying a Used Engine Control Module: What You Must Know

Purchasing a used OEM ECM is an excellent way to save a significant amount of money, but you must follow specific steps to ensure it will work in your vehicle.

1. Match The Part Number Exactly

The most critical step is to match the OEM part number from your original ECM to the replacement unit. Honda uses many different ECMs for the same vehicle depending on the trim level, drivetrain, and factory options. The part numbers provided in the initial data, 37820-RLV-C41 and 37820-RLV-C42, are specifically for the FWD Touring models equipped with the pre-crash system. Using an ECM from an AWD or LX model in a FWD Touring will likely cause features to malfunction or prevent the vehicle from operating correctly. Always verify the number on your specific module before buying.

2. Plan for Programming

Because the ECM is tied to the immobilizer, you cannot simply swap it. You have three main options to get the replacement module programmed to your vehicle:

• Honda Dealership: A dealer can always program a new or used ECM to your vehicle. This is often the most straightforward but can be the most expensive option.
• Independent Repair Shop: Many independent shops that specialize in Honda or advanced diagnostics have the necessary tools. They need a J2534 Pass-Thru device and a subscription to Honda's i-HDS software to perform the VIN write and immobilizer re-learn procedure.
• Mail-In Cloning Service: Several companies offer a service where you mail in both your original (faulty) ECM and the used replacement. They transfer or clone the key and VIN data from your old module to the replacement. When you receive it back, the replacement ECM is plug-and-play, requiring no further programming.

3. Inspect the Used Part

When your used ECM arrives, inspect it for any signs of physical damage. Check for corrosion on the casing, bent pins on the connectors, or any evidence that the case has been opened, which could indicate a prior failed repair attempt.

Cost Comparison for a 2017-2019 Pilot ECM

Step-by-Step Replacement Guide (Physical Swap)

The physical replacement of the ECM is relatively simple. The module is located in the front right-hand (passenger) side of the engine compartment.

1. Disconnect the Battery: Use a wrench to loosen the nut on the negative battery terminal and pull the cable off.
2. Locate the ECM: Open the hood and find the ECM on the passenger side of the engine bay. It is a silver metal box with several large electrical connectors.
3. Disconnect Wiring Harnesses: Carefully press the release tabs on each electrical connector and pull them straight out from the ECM.
4. Unbolt the ECM: Remove the bolts or nuts holding the ECM bracket in place.
5. Install the New ECM: Mount the replacement ECM and secure it with the bolts.
6. Reconnect Harnesses and Battery: Plug the wiring harnesses back into the new ECM until they click securely. Reconnect the negative battery terminal.
7. Arrange for Programming: At this point, the vehicle will not start. It must be towed to a dealer or shop for programming, unless you used a mail-in cloning service.

Frequently Asked Questions (FAQ)