AUTOOL AS501 · Six-Mode Brake Fluid Tester
Reach Tight Reservoirs for Fluid Checks
Screen brake-fluid water content after selecting the matching DOT or ENV mode. AS501 reaches confined reservoirs with a 260 mm flexible probe and returns water-content and fluid-grade guidance in about 10 seconds. The 1.8-inch backlit display keeps the selected fluid mode and completed result visible during service.
- DOT 3 / 4 / 5 / 5.1 / ENV Modes
- About 10-Second Water Screen
- 260 mm Flexible Probe
- 1.8-Inch Backlit Display
- 2 × AA Battery Power

Key Features
Six-Mode Brake Fluid Moisture Tester with a Flexible Probe
Six Fluid Modes
Select DOT 3, DOT 4, DOT 5, DOT 5.1, ENV 4 or ENV 6 before testing so the result uses the intended fluid setting.
10-Second Test Cycle
The tester completes a brake fluid water test in about 10 seconds and displays water content and fluid grade.
1.8-Inch Backlit Display
The backlit screen keeps the selected mode and result readable in bright or dim service areas.
260 mm Flexible Probe
The flexible gooseneck helps reach reservoir openings while keeping the handheld display visible.
Portable AA Power
Two 1.5 V AA batteries power the tester without a vehicle connection.
3 Years Warranty Support
Main unit: 3-year warranty. Standard accessories: 1-year warranty. Warranty Policy.
Safe Use
Match the Fluid Before Every Test
Fluid Selection and Probe Care
Select the exact brake-fluid mode, clean the probe between samples and use the displayed moisture/grade value for quick fluid screening. It is not a standardized wet boiling-point result.
Specifications
Fluid Modes and Tester Specifications
| Specification | Value |
|---|---|
| Supported fluids | DOT 3, DOT 4, DOT 5, DOT 5.1, ENV 4, ENV 6 |
| Power supply | 2 × 1.5 V AA batteries |
| Operating temperature | -10°C to 50°C |
| Storage temperature | -20°C to 60°C |
| Probe length | 260 mm |
Manual & Support
Find the Manual and Fluid-Test Guidance
AUTOOL AS501 User Manual
Open the PDF manual for AUTOOL AS501 fluid mode selection, flexible-probe testing, result interpretation, battery setup, probe cleaning, safe handling and troubleshooting support.

Package Contents
See What Comes in the Box
- Package ContentsAUTOOL AS501 tester, retail packaging and the accessories shown for the current sales package; confirm the selected regional package before ordering.
Buyer Questions
Fluid Fit, Method and Result Questions
Which brake fluids can AS501 test?
Select the matching mode for DOT 3, DOT 4, DOT 5, DOT 5.1, ENV 4 or ENV 6 before placing the clean probe in the fluid.
How long does a test take?
The manufacturer’s procedure states that the result appears after about 10 seconds.
Does the reading replace a boiling-point test?
No. AS501 screens moisture/grade through its supported method; follow the vehicle or fluid maker’s service procedure when a boiling-point test or another confirmation is required.
How should the probe be handled between tests?
Clean the probe after each sample and avoid transferring residue between different fluid types.




