Brake Fluid Checker Pen | 5-LED DOT3/4/5 Moisture Tester
Brake Fluid Checker Pen | 5-LED DOT3/4/5 Moisture Tester
Brake Fluid Checker Pen – 5-LED DOT3/4/5 Moisture Tester
Keep your braking system in top condition with this compact Brake Fluid Checker Pen. In just seconds, its 5-LED indicator shows you the exact moisture content of your brake fluid — helping you know precisely when it's time for a change. Compatible with DOT3, DOT4, and DOT5 fluids, it's the must-have diagnostic tool for cars, trucks, and motorcycles.
Made in Mainland China.
Key Features
- 5-LED Color Display – Instant visual readout of brake fluid moisture level from safe to critical
- DOT3 / DOT4 / DOT5 Compatible – Works with all common brake fluid types
- Auto Shut-Off – Automatically powers down after 12 seconds to conserve battery
- Compact Pen Design – Lightweight and portable; fits in any toolbox, glove box, or garage drawer
- Simple One-Button Operation – Press, dip, and read — no calibration required
- Accurate Moisture Detection – Measures water content from below 1% up to 4%+
- Requires 1 × AAA 1.5V battery (not included)
LED Indicator Guide
| LEDs Lit | Moisture Level | Status |
|---|---|---|
| 🟢 | No water detected | Battery OK / Fluid Good |
| 🟢🟡 | Below 1% | Fluid is in good condition |
| 🟢🟡🟡 | ~2% | Monitor fluid; change soon |
| 🟢🟡🟡🔴 | ~3% | Replacement recommended |
| 🟢🟡🟡🔴🔴 | 4%+ | Replace fluid immediately |
Note: LED readings are for reference guidance only.
How to Use
- Remove the cap from the test pen and open the brake fluid reservoir cap on your vehicle.
- Immerse the test probe into the brake fluid in the reservoir.
- Press and hold the power button for 1 second — the LEDs will display the moisture reading.
- The pen automatically shuts off after 12 seconds.
- After use, rinse the test probe with clean water and replace the cap.
Important Notes
- If the green LED does not illuminate after pressing the power button, replace the AAA battery.
- Rinse the test probe with clean water after each use.
- Do not leave brake fluid reservoir open for extended periods — brake fluid absorbs moisture from the air.
What's in the Box
- 1 × Brake Fluid Checker Pen (AAA battery not included)
Related Products You May Like
- 4-Pack Deer Whistle Wildlife Alert Devices for Vehicles
- 2-Pack S-Hook Brake Caliper Hangers with Rubber Tips
- 25-in-1 Precision Magnetic Screwdriver Set | Pro Repair Kit
Learn more: FuelEconomy.gov driving efficiency guidance
Frequently Asked Questions
Q: What brake fluid types does this brake fluid checker pen support?
A: This brake fluid tester is compatible with DOT3, DOT4, and DOT5 brake fluids, making it suitable for most cars, trucks, and motorcycles.
Q: Do I need to calibrate the brake fluid checker pen before use?
A: No calibration is required. Simply insert a AAA battery, dip the probe into your brake fluid reservoir, and press the power button for a one-second reading. The 5-LED display instantly shows the moisture level.
Q: How do I know when to replace my brake fluid based on the LED reading?
A: When 4 LEDs light up (green, yellow, yellow, red), moisture is approaching 3% and replacement is recommended. When all 5 LEDs illuminate, moisture exceeds 4% and the brake fluid should be replaced immediately for safe vehicle operation.
Q: What battery does the brake fluid tester use?
A: It requires one AAA 1.5V battery, which is not included. Open the battery cover by following the arrow direction indicated on the pen body.