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White pen-shaped brake fluid tester with silver probe, black display window and three coloured indicator lights

KAIWEETS Brake Fluid Tester Pen Corrosion Resistant Probe DOT3 DOT4 DOT5.1

SKU CH-9TWR-GN490

Measures brake fluid moisture from 0% to 4% with ±0.3% accuracy for DOT3, DOT4 and DOT5.1 fluids

  • Key featuresCorrosion Resistance, Polypropylene, 0% - 4%, ±0.3%, 1*brake
  • Overall height25.2 L x 6.5 W x 4 H centimeters
  • Overall width25.2 L x 6.5 W x 4 H centimeters
  • Overall length25.2 L x 6.5 W x 4 H centimeters
  • Product weight0.118 kg
  • Corrosion-resistant probe ensures lasting accuracy
  • ±0.3% precision across 0-4% moisture range
  • Tests DOT3, DOT4 and DOT5.1 brake fluids
  • Data hold, buzzer alarm and three-colour backlight aid reading
  • Auto power-off after 5 minutes and low-battery alert

Brake Fluid Tester Pen

The KAIWEETS brake fluid tester pen measures moisture content in DOT3, DOT4 and DOT5.1 fluids with a corrosion-resistant probe. It is intended for professional mechanics and DIY enthusiasts who need a compact, battery-powered tool for routine brake-system checks.

Capacity and Headroom

The tester reads from 0% to 4% moisture with an accuracy of ±0.3%, covering the range where brake fluid remains effective. It cannot measure humidity above 4%, so severely contaminated systems fall outside its useful range.

Thermals Noise and Power Draw

The device operates on two 1.5 V AAA batteries and functions in ambient temperatures from 0 to 40 °C. An automatic shutdown after five minutes of inactivity conserves power, while a low-battery reminder ensures the unit is ready when needed.

How it compares

Measured against everything we stock in Brake Testers & Gauges, at today’s prices. Recalculated every night.

Price $31.99
Pricier than about 79% of the 18 comparable items (median $17.49).

Specifications

Product
Brand nameKAIWEETS
Size & build
Overall height25.2 L x 6.5 W x 4 H centimeters
Overall width25.2 L x 6.5 W x 4 H centimeters
Overall length25.2 L x 6.5 W x 4 H centimeters
Product weight0.118 kg

Questions about this item

Will the corrosion-resistant probe still give accurate readings if I keep using my older DOT3 brake fluid?

The probe is calibrated for DOT3, DOT4 and DOT5.1 and measures moisture from 0% to 4% with ±0.3% accuracy regardless of fluid age.

How do I know the tester is working correctly once I turn it on?

The three-colour backlight shows the moisture level, the buzzer sounds above 3% and the data-hold button locks the reading for review.

Does the box include the two AAA batteries or do I need to buy them separately?

The package contains the tester pen and 2 AAA batteries so you can start testing immediately.

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