Honda K20A Vehicle Speed Sensor 78410-S6M-N01

Honda K20A2 Vehicle Speed Sensor 78410-S6M-N01 — 2002-2004 Acura RSX Type-S

When your K20A2 VSS signal drops out, your speedometer goes dead, cruise control disengages, and your ECU starts throwing codes that can mask everything else you're chasing. This is the genuine Honda OEM replacement — part number 78410-S6M-N01 — and it's the exact sensor your RSX Type-S or K-swap needs to restore clean speed data to every system that depends on it.

Mounted at the rear of the transmission, this sensor feeds VSS pulses to your speedometer, ABS module, ECU, and cruise control. When it's working right, you don't think about it. When it's not, your whole drivability picture falls apart. The OEM unit matters here because aftermarket alternatives are notorious for signal noise and calibration drift — both of which your ECU will notice before you do.

Why this OEM sensor and not a cheaper alternative

• Exact factory calibration — Honda part 78410-S6M-N01 matches the original pulse-per-revolution spec your K20A2 ECU expects. Off-brand sensors can read within tolerance on a multimeter and still trigger limp mode or disable VTEC engagement under load.
• Direct plug-and-play fit — molded OEM connector seats and locks without modification on 2002-2004 RSX Type-S, 2004-2005 Civic Si, and any K-swap running a K20A2-type transmission with a compatible conversion harness (Hybrid Racing Conversion Harness or Rywire Engine Harness).
• Pre-installed O-ring, sealed terminals — weather-pack construction keeps fluid and debris out. One less thing to worry about on a track car or a build that lives outside.
• K-swap compatible — if you're dropping a K20A2 transmission into an EG, EK, DC2, or EF chassis, this is the sensor that lets the K-Series ECU communicate speed data cleanly through your conversion harness. No signal conditioning, no adapters.
• Fixes erratic speedometer readings — eliminates the needle bounce, false ABS triggers, and check-engine codes (P0500 / P0501) that come with a failing or missing VSS signal.

Who needs this part

If any of these apply to you, this sensor is what you're looking for:

• Your 02-04 RSX Type-S speedometer is reading erratically or not at all
• You're getting a P0500 or P0501 VSS code on a K20A2-equipped car
• You're finishing a K-swap into an older Honda chassis and need a working VSS signal for cruise control or ECU speed input
• You're doing a full transmission refresh and want to replace wear items while you're already in there
• You're prepping for a dyno tune and need clean sensor data before your tuner touches the map

Installation snapshot

Basic DIY skill level. 15-30 minutes. The O-ring comes pre-installed — reuse the OEM retaining bolt, torque to spec, and you're done. No cutting, no tuning, no calibration required on a stock K20A2 application.