Mazda Ignition Switch Problems: Turn-Key vs. Push-Button Failures (2004-2025)

The Most Important Question: Do You Have a Key or a Push-Button?

Before you diagnose a problem or buy a part, you must identify which ignition system is in your vehicle. This guide is split into two sections based on this critical difference. Using the wrong part will not work and could cause further electrical issues.

• Conventional Turn-Key Ignition: You insert a metal key into a lock cylinder on the steering column or dashboard and turn it to start the car. This system is common on the 2004-2013 Mazda 3 and 2006-2017 Mazda 5.
• Keyless Push-Button Start: You have a key fob that stays in your pocket or purse, and you press a button on the dashboard to start the engine. This system is used on the 2014-2018 Mazda 3, 2016-2022 Mazda CX-3, 2021-2025 Mazda CX-5, and 2016-2023 Mazda MX-5 Miata.

Part 1: Conventional Turn-Key Ignition Switch

This section applies to models like the 2004-2013 Mazda 3 and 2006-2017 Mazda 5 equipped with a standard key.

Key Details & Part Numbers

• Common Part Number: BP4K-66-151B (supersedes BP4K-66-151, BP4K-66-151A)
• What it is: This is only the electrical switch portion. It is a separate part from the mechanical lock cylinder where you insert your key.

Symptoms of a Failing Turn-Key Switch

Failure of the electrical switch is often intermittent and can be confused with a dead battery or bad starter.

• Car Won't Crank or Start: You turn the key to the 'START' position, and nothing happens. The dashboard lights may dim, but you hear no click from the starter.
• Intermittent Starting: The car fails to start randomly but may work fine on other attempts. Wiggling or jiggling the key in the ignition may help it make contact and start.
• Stalling While Driving: A worn switch can lose electrical contact due to vibration, cutting power to the ignition system and causing the engine to shut off unexpectedly.
• Accessories Don't Work Correctly: The radio, power windows, or climate controls may not work in the 'ACC' or 'ON' positions, or they may cut out intermittently.
• Key is Hard to Turn or Gets Stuck: While often a sign of a worn mechanical lock cylinder, it can also be related to the switch binding behind it.

Diagnosis & Replacement

A common issue on older Mazda 3 models is an intermittent no-start where wiggling the key helps. This points directly to wear inside the electrical switch or the mechanical cylinder. The switch itself is typically held to the back of the lock cylinder housing by small screws and is a straightforward part to replace once the steering column covers are removed.

Part 2: Keyless Push-Button Start Switch

This section applies to models like the 2014+ Mazda 3, CX-3, CX-5, and MX-5 Miata with a push-to-start button.

Key Details & Part Numbers

• Common Part Number: BJS7-66-3S0 (also listed as BJS7663S0)
• What it is: The physical button on the dashboard that you press to start the car.

Symptoms of a Failing Push-Button Switch

• Flashing Amber/Orange Light: The light on the start button may flash amber instead of turning green when you press the brake. While this can mean many things, it indicates a fault in the starting system if the batteries are known to be good.
• Intermittent or No Start: You press the button and nothing happens, or it only works after multiple presses.
• Engine Stalls or Accessories Stay On: In rare cases, the switch can fail internally, causing the engine to stall or preventing the car from fully shutting down, leaving it in accessory mode and draining the battery.
• 'Key Not Detected' Warning: If the fob battery is good, this message could point to a problem with the car's keyless receiver or the ignition switch itself.

Diagnosis & Replacement

Besides checking the batteries, also check the brake light switch. The system requires a signal that the brake pedal is pressed to allow the engine to start. If your brake lights aren't working, the car won't start, which can be mistaken for an ignition switch issue. The push-button switch itself is usually held in the dash by clips and is easy to access and replace once the surrounding trim is removed.

Known Issues, TSBs, and Recalls

• TSB 05-007/15: Some older models (like the 2013 CX-5) had an issue where the ignition would get stuck in accessory mode, draining the battery. This was caused by a faulty switch in the automatic transmission shifter mechanism, not the ignition switch on the dash.
• Airbag Recall (2024-2025 Models): A recall was issued for some 2024-2025 Mazda 3 and CX-30 vehicles where leaving the ignition in the 'ON' position for an extended period without the engine running could drain the battery. Upon jump-starting, the airbag control unit could malfunction, disabling the airbags. This is a software issue, not a direct failure of the switch.

Buying a Used Ignition Switch

Purchasing a used OEM ignition switch is a smart way to save money, especially since aftermarket electronic components can be unreliable. Here’s what to look for:

• For Turn-Key Switches (BP4K-66-151B): You are buying the electrical switch only, not the lock cylinder. Visually inspect the connector pins for any signs of corrosion or burning. Ensure the plastic housing is not cracked.
• For Push-Button Switches (BJS7-66-3S0): Since failure is electronic, a visual inspection is less helpful. The most important thing is to match the part number exactly. Check that the button has a clean, crisp feel and isn't physically damaged. Since it doesn't require programming, it's a very safe used part to purchase.
• Why Used OEM? Original Equipment Manufacturer (OEM) parts are built to a higher quality standard than most cheap aftermarket alternatives. For a critical electronic part like an ignition switch, sticking with a genuine Mazda part—even a used one—ensures proper function and longevity.

Cost Comparison

Shop labor for replacement typically runs from $50 to $150, depending on the model and accessibility.

Frequently Asked Questions