Indmar Marine Denso O2 Sensor – MEFI6 Service | Part #556162D

Keep your Indmar engine running at peak efficiency with this genuine Denso oxygen sensor, specifically selected for MEFI6 engine management system service. The O2 sensor is one of the most important feedback components in your fuel injection system — constantly monitoring exhaust oxygen levels and sending real time data to the MEFI6 ECU to maintain the perfect air/fuel ratio for performance, fuel economy, and emissions compliance.

Compatible with: Indmar marine engines running the MEFI6 engine management system fitted to Malibu, Moomba, Supra, and Tige boats. Contact us to verify fitment for your specific model year before ordering.

What is the MEFI6 engine management system?
MEFI stands for Marine Engine Fuel Injection — a sophisticated engine management system developed specifically for marine applications. The MEFI6 is the sixth generation of this system and represents the most advanced version, offering:

• Precise fuel injection control for optimal performance
• Real time engine monitoring and fault detection
• Improved fuel efficiency over earlier MEFI generations
• Enhanced emissions control to meet modern marine standards
• Diagnostic capability for faster, more accurate servicing

The O2 sensor is a critical input to the MEFI6 system — without accurate oxygen data the ECU cannot correctly adjust fuel delivery, leading to rich or lean running conditions.

Why Denso?
Denso is one of the world's leading manufacturers of oxygen sensors — supplying OEM sensors to major automotive and marine manufacturers globally. The Denso O2 sensor specified for MEFI6 service delivers:

• OEM-level accuracy and response time
• Superior durability in the harsh marine exhaust environment
• Correct electrical specifications for seamless MEFI6 integration
• Reliable performance across the full engine operating temperature range

Never substitute a generic or automotive O2 sensor — incorrect sensor specifications can confuse the MEFI6 ECU and cause poor running, fault codes, and failed emissions checks.

Signs your O2 sensor needs replacing:

• Check engine light or fault codes on your MEFI6 display
• Rich running — black smoke, strong fuel smell in exhaust
• Lean running — hesitation, popping, or backfiring under load
• Poor fuel economy — noticeably increased fuel consumption
• Rough idle or unstable engine at low RPM
• Failed emissions check

How often should you replace it?
O2 sensors don't have a fixed replacement interval but should be inspected at every major service. Sensors degrade over time as the sensing element becomes contaminated by exhaust deposits. If your MEFI6 is logging O2 sensor fault codes or your engine is running poorly despite other systems checking out — the O2 sensor is the first place to look.

Pro tip: When replacing your O2 sensor always use an anti-seize compound on the threads before installation. Exhaust heat causes O2 sensor threads to seize in the bung over time — making future removal extremely difficult. A small amount of anti-seize now saves a major headache at the next service.

Features:

• Genuine Denso OEM specification oxygen sensor
• Designed for Indmar MEFI6 engine management system service
• Correct electrical specifications for MEFI6 integration
• Superior durability in marine exhaust environments
• Real time exhaust oxygen monitoring for optimal fuel delivery
• Direct replacement — no modifications needed

Part Number: 556162D