2019 Honda CR-V ECM: Decoding Failure, Oil Dilution Updates, and Replacement Programming

Critical: Programming is Required

Known Issues for the 2019 Honda CR-V ECM

For this specific vehicle, some of the most common "ECM problems" are actually software issues that Honda has addressed. Before replacing the module for a performance-related issue, ensure the correct software updates have been performed.

Fuel-in-Oil Dilution Problem

A widely recognized issue for the 1.5L turbo engine is fuel diluting the engine oil, particularly in cold climates or with frequent short trips. This happens when the engine doesn't warm up quickly enough to evaporate all the gasoline from the cylinders, allowing it to seep past the piston rings and into the oil pan. Symptoms include a rising oil level on the dipstick and a smell of gasoline in the oil. Honda issued software updates for the ECM that adjust engine and transmission parameters to allow the engine to warm up faster, reducing the chances of dilution. 🎬 Watch: A mechanic explains the Honda oil dilution issue A class-action lawsuit was filed regarding this issue that includes 2019-2023 CR-V models.

Battery Drain (Service Bulletin 19-039)

Honda issued a product update for some 2019 CR-V models due to a software error in the ECM. The module was programmed to perform an evaporative (EVAP) system leak check five hours after the vehicle was shut down. However, due to the error, the ECM would not go back into its low-power "sleep mode" after the check was complete. This would cause a parasitic drain that could leave the battery dead after the vehicle was parked for an extended period. 🎬 See how to fix this hidden battery drain problem The fix is a software update performed by a dealer or qualified shop.

Symptoms of a Failing ECM

Beyond the specific software issues above, the ECM itself can fail. Here are the common signs of a hardware failure:

• Check Engine Light: The check engine light is on, and you may find codes specifically pointing to an internal computer fault, such as P1607 (ECM/PCM Internal Circuit Failure). It can also throw codes for sensors that are actually working correctly.
• Engine Misfires or Runs Rough: The engine may stutter, misfire, or idle erratically. This can be related to the oil dilution issue, triggering codes like P030X (Cylinder Misfire) and P0172 (Fuel System Too Rich).
• Car Will Not Start: The engine may crank but refuse to start. If the immobilizer light is flashing, it's a sign the ECM is not communicating with the security system.
• Poor Performance and Fuel Economy: You might notice a sudden drop in gas mileage or a lack of acceleration as the ECM fails to properly manage the air-fuel mixture.
• Transmission Shifting Problems: The ECM communicates with the transmission controller. A faulty ECM can send bad data, leading to harsh or delayed shifts.

Buying a Used Engine Control Module

Since new aftermarket or remanufactured ECMs for this specific vehicle are not readily available, a used OEM module is the most common and cost-effective alternative to a new one from the dealer. Here’s what to look for:

• Match Part Numbers Exactly: The most critical step is to match the part number on your original ECM to the number on the used unit. The correct part numbers for this application are 37820-5PA-654, 37820-5PA-655, 37820-5PA-652, and 37820-5PA-653. Part number 37820-5PA-654 often supersedes the earlier numbers.
• Physical Inspection: Check the used module for any signs of physical damage, such as a cracked case or bent connector pins. Avoid any units with signs of water intrusion or corrosion.
• Budget for Programming: Remember that the cost of the part is not the final cost. You MUST factor in the price of having the module professionally programmed to your vehicle.
• Source from a Reputable Seller: Purchase from a supplier that offers a warranty. This protects you in case the module is dead on arrival.

Replacement and Programming Procedure

ECM Location

On most modern Hondas, the ECM is located inside the passenger cabin to protect it from the elements. Look for it behind the glove box or in the center console area. It is typically held in place by a few 10mm bolts.

Programming the Replacement ECM

This process, often called an "Immobilizer Relearn" or "Replace ECM/PCM" function, syncs the new computer with your vehicle's immobilizer and keys.

• Who can do it? A Honda dealership or a well-equipped independent auto repair shop. Some mobile automotive locksmiths may also have the required tools, such as an Autel MaxiIM or Launch X431 scanner.
• What's involved? A technician connects a professional scan tool to the vehicle's OBD-II port. The tool's software guides them through a series of steps to register the new ECM's identity with the immobilizer control unit. This ensures the car recognizes its own keys and allows the engine to start.
🎬 Watch: How a professional performs a Honda ECM swap

Cost Breakdown

Costs can vary by location and shop, but here is a general estimate:

Frequently Asked Questions (FAQ)