{"id":40035,"date":"2023-11-20T14:30:45","date_gmt":"2023-11-20T06:30:45","guid":{"rendered":"https:\/\/shop.autooltech.com\/?post_type=product&p=40035"},"modified":"2026-05-20T03:05:54","modified_gmt":"2026-05-20T11:05:54","slug":"autool-as502-car-brake-fluid-tester","status":"publish","type":"product","link":"https:\/\/autoolstore.com\/nb\/product\/autool-as502-car-brake-fluid-tester\/","title":{"rendered":"AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing"},"content":{"rendered":"
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AUTOOL AS502<\/div>\n

Product Overview<\/h2>\n

The AUTOOL AS502 is a handheld brake fluid tester for checking the water content percentage in DOT3, DOT4, and DOT5.1 brake fluid. It combines pressure boost detection, normal and expert test modes, a 260mm flexible probe, and a 2.8-inch backlit LCD screen to help users judge brake fluid condition before replacement.<\/p>\n

\n DOT3 \/ DOT4 \/ DOT5.1<\/span>\n Water Content Testing<\/span>\n Normal \/ Expert Mode<\/span>\n 260mm Flexible Probe<\/span>\n <\/div>\n
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2.8-inch<\/span>Backlit Display<\/span><\/div>\n
6V<\/span>4 \u00d7 AAA Batteries<\/span><\/div>\n
10s<\/span>Response Time<\/span><\/div>\n
3 Years<\/span>Main Unit Warranty<\/span><\/div>\n <\/div>\n <\/div>\n
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\n \"AUTOOL\n \n Click to enlarge<\/span>\n <\/figure>\n
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Before You Order And Use<\/div>\n

Before You Order And Use<\/h2>\n

Review the brake-fluid type, battery, test interval, probe cleaning, and storage notes before using the AS502 brake fluid tester.<\/p>\n <\/div>\n

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Brake Fluid Water Test<\/h3>\n

AS502 is designed to test the water content percentage in brake fluid. It is not an engine oil, transmission fluid, or power steering fluid tester.<\/p>\n <\/article>\n

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Routine Check Suggestion<\/h3>\n

For routine maintenance, checking brake fluid around every 40,000 km is recommended, depending on vehicle condition and service requirements.<\/p>\n <\/article>\n

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Use Supported Fluids Only<\/h3>\n

Use AS502 with supported brake fluid types. Normal mode is for DOT3, DOT4, and DOT5.1 brake fluid; expert mode is for selected DOT4 brands.<\/p>\n <\/article>\n

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Install 4 AAA Batteries<\/h3>\n

The tester uses 6V power from 4 \u00d7 1.5V AAA batteries. Install batteries with the correct polarity before operation.<\/p>\n <\/article>\n

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Clean The Probe<\/h3>\n

Wipe the probe clean before each measurement and clean it after use to avoid fluid residue affecting later tests.<\/p>\n <\/article>\n

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Store Dry<\/h3>\n

If the tester will not be used for a long time, remove all batteries and store the unit in a dry place at normal room temperature.<\/p>\n <\/article>\n <\/div>\n <\/section>\n\n

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Key Features<\/div>\n

Key Features<\/h2>\n

AS502 focuses on fast brake fluid water-content testing with pressure boost detection, two test modes, a flexible stainless-steel probe, comfortable handheld control, and a readable backlit screen.<\/p>\n <\/div>\n

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Pressure Boost Detection<\/h3>\n

Pressure boost detection technology helps improve test stability and supports clearer brake fluid water-content measurement.<\/p>\n <\/article>\n

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Multiple Brake Fluid Support<\/h3>\n

Normal mode supports DOT3, DOT4, and DOT5.1 brake fluid, making AS502 suitable for common vehicle brake fluid checks.<\/p>\n <\/article>\n

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Normal And Expert Modes<\/h3>\n

Switch between standard brake-fluid type testing and expert mode for selected DOT4 brands when more targeted fluid selection is needed.<\/p>\n <\/article>\n

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260mm Flexible Probe<\/h3>\n

The 260mm gooseneck probe helps reach the brake fluid reservoir more easily during vehicle maintenance.<\/p>\n <\/article>\n

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304 Stainless Steel Outer Hose<\/h3>\n

The probe hose outer layer uses 304 stainless steel for oil resistance, oxidation resistance, and corrosion resistance.<\/p>\n <\/article>\n

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2.8-inch Backlit Display<\/h3>\n

The 2.8-inch LCD backlit display makes the result easier to read in bright or low-light working conditions.<\/p>\n <\/article>\n <\/div>\n\n

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\"AUTOOL\n Click to enlarge<\/span>\n <\/figure>\n
\"AUTOOL\n Click to enlarge<\/span>\n <\/figure>\n
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Compatibility And Fitment<\/div>\n

Compatibility And Fitment<\/h2>\n

AS502 offers two detection modes. Select the correct mode according to the brake fluid type or supported DOT4 brand before testing.<\/p>\n

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Normal Mode<\/span>Suitable for DOT3, DOT4, and DOT5.1 brake fluid water-content testing.<\/strong><\/div>\n
Expert Mode<\/span>Suitable for selected DOT4 brands, including MOTUL, ATE, FERODO, MOBIL, BREMBO, TRW, BOSCH, CASTROL, TOTAL, VALEO, FUCHS, and TEXTAR.<\/strong><\/div>\n
Selection Check<\/span>Do not treat expert mode as universal support for every fluid brand. Match the on-screen mode to the fluid being tested.<\/strong><\/div>\n <\/div>\n <\/div>\n
\n \"AUTOOL\n \n Click to enlarge<\/span>\n <\/figure>\n <\/div>\n <\/section>\n\n
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Specifications<\/div>\n

AUTOOL AS502 Product Specifications<\/h2>\n

AS502 uses 6V battery power, a 2.8-inch display, 10-second response, pressure boost detection technology, and a 260mm 304 stainless-steel probe hose for brake fluid water-content checks.<\/p>\n <\/div>\n\n

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Core Specifications<\/td><\/tr>\n
Product<\/td>AUTOOL AS502 Brake Fluid Tester<\/td><\/tr>\n
Testing Object<\/td>Brake fluid water content percentage<\/td><\/tr>\n
Detection Technology<\/td>Pressure boost detection technology<\/td><\/tr>\n
Operating Principle<\/td>Brake fluid water-content testing<\/td><\/tr>\n
Supported Brake Fluid<\/td>DOT3 \/ DOT4 \/ DOT5.1 in normal mode; selected DOT4 brands in expert mode<\/td><\/tr>\n
Display<\/td>2.8-inch LCD backlit display<\/td><\/tr>\n
Power Supply<\/td>6V, 4 \u00d7 1.5V AAA batteries<\/td><\/tr>\n
Test Duration<\/td>10-second response<\/td><\/tr>\n
Probe \/ Test Cable Length<\/td>260mm \/ 26cm<\/td><\/tr>\n
Hose Material<\/td>304 stainless steel outer hose<\/td><\/tr>\n
Operating Temperature<\/td>-10\u00b0C~60\u00b0C<\/td><\/tr>\n
Modes<\/td>Normal Mode \/ Expert Mode<\/td><\/tr>\n
Auto Power Off<\/td>Automatically powers off after 5 minutes of no activity<\/td><\/tr>\n
Main Unit Size<\/td>175 \u00d7 72 \u00d7 29mm<\/td><\/tr>\n
Warranty<\/td>3 years for the main unit; 1 year for included accessories<\/td><\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n
\n \"AUTOOL\n \n Click to enlarge<\/span>\n <\/figure>\n <\/div>\n
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\n Core Specifications<\/summary>\n
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Product<\/span>AUTOOL AS502 Brake Fluid Tester<\/strong><\/div>\n
Testing Object<\/span>Brake fluid water content percentage<\/strong><\/div>\n
Detection Technology<\/span>Pressure boost detection technology<\/strong><\/div>\n
Operating Principle<\/span>Brake fluid water-content testing<\/strong><\/div>\n
Supported Brake Fluid<\/span>DOT3 \/ DOT4 \/ DOT5.1 in normal mode; selected DOT4 brands in expert mode<\/strong><\/div>\n
Display<\/span>2.8-inch LCD backlit display<\/strong><\/div>\n
Power Supply<\/span>6V, 4 \u00d7 1.5V AAA batteries<\/strong><\/div>\n
Test Duration<\/span>10-second response<\/strong><\/div>\n
Probe \/ Test Cable Length<\/span>260mm \/ 26cm<\/strong><\/div>\n
Hose Material<\/span>304 stainless steel outer hose<\/strong><\/div>\n
Operating Temperature<\/span>-10\u00b0C~60\u00b0C<\/strong><\/div>\n
Modes<\/span>Normal Mode \/ Expert Mode<\/strong><\/div>\n
Auto Power Off<\/span>Automatically powers off after 5 minutes of no activity<\/strong><\/div>\n
Main Unit Size<\/span>175 \u00d7 72 \u00d7 29mm<\/strong><\/div>\n
Warranty<\/span>3 years for the main unit; 1 year for included accessories<\/strong><\/div>\n <\/div>\n <\/details>\n <\/div>\n <\/section>\n\n\n\n
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How To Use<\/div>\n

How To Use<\/h2>\n

Install batteries, clean the probe, select the correct brake fluid type, immerse the probe, and start the test. The screen displays the water content percentage and replacement status.<\/p>\n <\/div>\n

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Install Batteries<\/h3>\n

Open the rear battery cover, insert 4 \u00d7 1.5V AAA batteries with correct polarity, then close the cover securely.<\/p>\n <\/article>\n

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Power On<\/h3>\n

Long press the power button for more than 2 seconds to turn on the tester.<\/p>\n <\/article>\n

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Clean The Probe<\/h3>\n

Wipe the probe clean before each measurement to avoid residue affecting the result.<\/p>\n <\/article>\n

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Open The Reservoir<\/h3>\n

Open the brake fluid reservoir cap and prepare the brake fluid sample area for testing.<\/p>\n <\/article>\n

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Select Fluid Type<\/h3>\n

Press the selection button to choose DOT3, DOT4, DOT5.1, or an available expert-mode DOT4 brand.<\/p>\n <\/article>\n

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Immerse And Test<\/h3>\n

Submerge the probe into the brake fluid, press the test button, and read the displayed water content percentage and status indicator.<\/p>\n <\/article>\n <\/div>\n

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Result Reading And Use Notes<\/h3>\n