Oil Pressure Switch | Honda CB350F / CB400F / CB500K / CB550 / CB750

Oil Pressure Switch | Honda CB350F / CB400F / CB500K / CB550 / CB750

Replacement oil pressure switch for vintage Honda four-cylinder and twin motorcycles. Restores proper oil pressure warning light function so you know immediately when oil pressure drops below safe operating levels.

Why You Need This

The oil pressure warning light is your engine's last line of defense — when it comes on, oil pressure has dropped below the safe threshold and engine damage can follow quickly. A failed or unreliable oil pressure switch means you lose that warning entirely. Common symptoms of a bad switch include the oil light staying on at all RPMs, the light never coming on at all (even at key-on), or intermittent flickering at idle.

This replacement switch is made in Japan and is a direct drop-in for the original. No modifications needed.

Specifications

Installation

Difficulty: Beginner

1. For best results, install the oil pressure switch during an oil change so the crankcase area is clean and accessible.
2. Disconnect the wire terminal from the old switch.
3. Unscrew the old switch from the crankcase using a wrench.
4. Apply a small amount of thread sealant or blue thread locker to the threads of the new switch.
5. Thread the new switch into the crankcase by hand first, then snug with a wrench. Do not overtighten.
6. Reconnect the wire terminal. Before installation, inspect the condition of the electrical connector — replace if corroded, loose, or damaged.
7. Start the engine and verify the oil light comes on at key-on, then goes off within a few seconds of the engine running.

Frequently Asked Questions

My oil light stays on after the engine is running — is the switch bad?

Not necessarily. A persistent oil light usually indicates an actual oil pressure problem, not a bad switch. Check your oil level first, then inspect the oil filter for clogs. If oil level and filter are fine, test the switch by disconnecting the wire — if the light goes off with the wire disconnected and the engine running, the switch may be faulty. If the light stays on even with the wire disconnected, you have a wiring issue.

My oil light never comes on, even at key-on. Is the switch or the bulb?

With the key on and engine off, the oil light should come on (no oil pressure = switch grounds the circuit). If it doesn't, check the gauge bulb first — it may be burned out. If the bulb is good, disconnect the wire from the switch and ground it to the engine case. If the light comes on, the switch is bad. If it still doesn't come on, you have a wiring or bulb issue.

The oil light flickers at idle but goes off when I rev. Is that normal?

Some flickering at hot idle can be normal on high-mileage engines as oil thins when hot and pressure drops at low RPM. If the flicker is new or getting worse, check your oil level and consider switching to a slightly heavier weight oil. A failing oil pressure switch can also cause intermittent flickering — replacing it is a cheap first step to rule it out.

Does this fit the CB450 or CB500T twin?

No. This switch fits the Honda four-cylinder models (CB350F, CB400F, CB500K, CB550) and the CB750 series only. The CB450 and CB500T twins use a different oil pressure switch — contact us if you need help finding the right part for your bike.

You Might Also Need

• Oil Filter w/ O-rings | Honda CB550 / CB750 — Replace during every oil change.
• Hondalock Thread Locker — Apply to the switch threads to prevent loosening and leaks.
• Oil Drain Plug Crush Washers — Replace the copper washer every oil change to prevent drips.
• Oil Filter Bolt | Honda CB550 / CB750 — Replace if stripped or damaged.

Last updated: April 2026