Honda K20A2 Crank Sensor 37500-PNB-003

Genuine Honda Crankshaft Position Sensor (37500-PNB-003) - K20A / K20A2

The crank sensor is what tells your ECU where the crankshaft is and how fast it's turning. Every ignition event and every injector pulse is timed off that signal, which means when the sensor fails, the engine doesn't run poorly, it stops running. This is the genuine Honda part, and it's the sensor most K-swaps end up needing since it matches the K20A and K20A2-style engine harnesses people build around.

What Failure Looks Like

Worth knowing, because a crank sensor fails in a way that's easy to misdiagnose as something more expensive.

The classic symptom is a car that cranks but won't start. Fuel pump primes, starter turns, nothing catches, because the ECU has no crank signal and won't fire anything without one.

Before it gets that far you'll often see intermittent stalling, especially once the engine is hot, since a marginal sensor degrades as it heats up and recovers when it cools. That's the frustrating stage where the car dies at a light, then starts fine twenty minutes later, and a shop can't reproduce it. You may also get a crank position sensor code, or a hesitation and misfire under load as the signal drops out.

If you've got a K-series that stalls hot and restarts cold, this sensor is one of the first things to look at.

The One Most K-Swaps Need

Practical note for anyone building rather than repairing. This is the sensor that matches K20A and K20A2-style engine harnesses, which is the wiring most K-swaps are built around.

So whether you're assembling a swap from parts, replacing a sensor of unknown history that came with a used engine, or troubleshooting a build that won't fire, this is generally the correct part. Worth confirming against your specific harness and engine combination, since swap wiring varies, but this is the common denominator.

Use The Genuine Sensor

Crank sensors are a spot where cheap parts genuinely bite people. The failure mode is intermittent before it's total, which means a marginal aftermarket sensor gives you a car that stalls unpredictably and takes days to diagnose because the fault comes and goes.

This is the exact part Honda spec'd. It's inexpensive relative to the time you'd spend chasing a signal problem, and on a swap where you're already troubleshooting multiple systems at once, having one component you don't have to question is worth a lot.

Fitment

2002-2004 Acura RSX Base and Type-S
2002-2005 Honda Civic Si (EP3)
2002-2009 Honda CR-V

Also compatible with most K20A and K20A2-style engine harnesses used in K-swaps.

Who Should Grab One

This is for anyone chasing a no-start or a hot stall on a K-series, and for the swap builder who'd rather put a known-good genuine sensor in than trust one that came attached to a used engine. It's cheap, it's easy to reach, and it's the difference between a car that runs and a car that doesn't. Grab one and take it off your list of suspects.

Fits: 2002-2004 Acura RSX, 2002-2005 Honda Civic Si, 2002-2009 Honda CR-V, plus most K20A and K20A2-style swap harnesses. Part number: 37500-PNB-003. Type: genuine Honda crankshaft position sensor.