AUTOOL AS502Product OverviewThe 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.DOT3 / DOT4 / DOT5.1 Water Content Testing Normal / Expert Mode 260mm Flexible Probe2.8-inchBacklit Display6V4 × AAA Batteries10sResponse Time3 YearsMain Unit Warranty Click to enlarge Click to enlargeBefore You Order And UseBefore You Order And UseReview the brake-fluid type, battery, test interval, probe cleaning, and storage notes before using the AS502 brake fluid tester.Brake Fluid Water TestAS502 is designed to test the water content percentage in brake fluid. It is not an engine oil, transmission fluid, or power steering fluid tester.Routine Check SuggestionFor routine maintenance, checking brake fluid around every 40,000 km is recommended, depending on vehicle condition and service requirements.Use Supported Fluids OnlyUse AS502 with supported brake fluid types. Normal mode is for DOT3, DOT4, and DOT5.1 brake fluid; expert mode is for selected DOT4 brands.Install 4 AAA BatteriesThe tester uses 6V power from 4 × 1.5V AAA batteries. Install batteries with the correct polarity before operation.Clean The ProbeWipe the probe clean before each measurement and clean it after use to avoid fluid residue affecting later tests.Store DryIf 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.Key FeaturesKey FeaturesAS502 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.Pressure Boost DetectionPressure boost detection technology helps improve test stability and supports clearer brake fluid water-content measurement.Multiple Brake Fluid SupportNormal mode supports DOT3, DOT4, and DOT5.1 brake fluid, making AS502 suitable for common vehicle brake fluid checks.Normal And Expert ModesSwitch between standard brake-fluid type testing and expert mode for selected DOT4 brands when more targeted fluid selection is needed.260mm Flexible ProbeThe 260mm gooseneck probe helps reach the brake fluid reservoir more easily during vehicle maintenance.304 Stainless Steel Outer HoseThe probe hose outer layer uses 304 stainless steel for oil resistance, oxidation resistance, and corrosion resistance.2.8-inch Backlit DisplayThe 2.8-inch LCD backlit display makes the result easier to read in bright or low-light working conditions. Click to enlarge Click to enlarge Click to enlarge Click to enlargeCompatibility And FitmentCompatibility And FitmentAS502 offers two detection modes. Select the correct mode according to the brake fluid type or supported DOT4 brand before testing.Normal ModeSuitable for DOT3, DOT4, and DOT5.1 brake fluid water-content testing.Expert ModeSuitable for selected DOT4 brands, including MOTUL, ATE, FERODO, MOBIL, BREMBO, TRW, BOSCH, CASTROL, TOTAL, VALEO, FUCHS, and TEXTAR.Selection CheckDo not treat expert mode as universal support for every fluid brand. Match the on-screen mode to the fluid being tested. Click to enlargeSpecificationsAUTOOL AS502 Product SpecificationsAS502 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.Core SpecificationsProductAUTOOL AS502 Brake Fluid TesterTesting ObjectBrake fluid water content percentageDetection TechnologyPressure boost detection technologyOperating PrincipleBrake fluid water-content testingSupported Brake FluidDOT3 / DOT4 / DOT5.1 in normal mode; selected DOT4 brands in expert modeDisplay2.8-inch LCD backlit displayPower Supply6V, 4 × 1.5V AAA batteriesTest Duration10-second responseProbe / Test Cable Length260mm / 26cmHose Material304 stainless steel outer hoseOperating Temperature-10°C~60°CModesNormal Mode / Expert ModeAuto Power OffAutomatically powers off after 5 minutes of no activityMain Unit Size175 × 72 × 29mmWarranty3 years for the main unit; 1 year for included accessories Click to enlarge Core SpecificationsProductAUTOOL AS502 Brake Fluid TesterTesting ObjectBrake fluid water content percentageDetection TechnologyPressure boost detection technologyOperating PrincipleBrake fluid water-content testingSupported Brake FluidDOT3 / DOT4 / DOT5.1 in normal mode; selected DOT4 brands in expert modeDisplay2.8-inch LCD backlit displayPower Supply6V, 4 × 1.5V AAA batteriesTest Duration10-second responseProbe / Test Cable Length260mm / 26cmHose Material304 stainless steel outer hoseOperating Temperature-10°C~60°CModesNormal Mode / Expert ModeAuto Power OffAutomatically powers off after 5 minutes of no activityMain Unit Size175 × 72 × 29mmWarranty3 years for the main unit; 1 year for included accessories How To UseHow To UseInstall 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.Install BatteriesOpen the rear battery cover, insert 4 × 1.5V AAA batteries with correct polarity, then close the cover securely.Power OnLong press the power button for more than 2 seconds to turn on the tester.Clean The ProbeWipe the probe clean before each measurement to avoid residue affecting the result.Open The ReservoirOpen the brake fluid reservoir cap and prepare the brake fluid sample area for testing.Select Fluid TypePress the selection button to choose DOT3, DOT4, DOT5.1, or an available expert-mode DOT4 brand.Immerse And TestSubmerge the probe into the brake fluid, press the test button, and read the displayed water content percentage and status indicator.Result Reading And Use Notes% shows the percentage of water content in brake fluid.OK indicates the brake fluid water content is good.! indicates a brake fluid water-content warning.× indicates replacement is suggested.0%-2% is displayed as a pass range, 2%-3% as a warning range, and above 3% as a replacement range.The tester automatically powers off after 5 minutes of no activity.Press and hold the power button for 2 seconds after measurement to turn off the tester. Click to enlarge Click to enlargeProduct ComparisonProduct ComparisonCompare AS502 with other AUTOOL automotive oil and fluid analyzers before choosing a tester for brake fluid water content, engine oil quality, transmission fluid, boiling point, or power steering fluid.AS502 FocusBrake fluid water-content testing with pressure boost detection, 2.8-inch backlit display, 6V power, 10-second response, 26cm test cable, and normal/expert mode support.AS501 DifferenceAS501 also tests brake fluid water content, but uses a 1.8-inch display, 3V power, and iron oxide hose material.AS503 / AS505AS503 is for engine oil quality by transmittance. AS505 is for automatic transmission fluid testing by transmittance.AS506 / AS507AS506 tests brake fluid boiling point. AS507 tests power steering fluid by transmittance.Decision CheckChoose according to the fluid type and test principle, not only by appearance. AS502 is the right choice when the target is brake fluid water content with normal and expert mode selection. Click to enlargeRelated ProductsRelated ProductsCompare related AUTOOL fluid testers for brake fluid water content, engine oil quality, transmission fluid, brake fluid boiling point, and power steering fluid testing. SALESelect options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS502 Car Brake Fluid Tester For Water Content TestingRated 0 out of 5(0) From US$30.00 Select options This product has multiple variants. The options may be chosen on the product page SALESelect options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS503 Engine Oil Tester with Digital DisplayRated 0 out of 5(0) From US$39.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS505 Exchanger Transmission Oil Tester with DisplayRated 0 out of 5(0) From US$49.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS506 Automobile Brake Fluid TesterRated 0 out of 5(0) From US$72.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS507 Power Steering Fluid Tester High Precision probeRated 0 out of 5(0) From US$30.00 Select options This product has multiple variants. The options may be chosen on the product page Manual And DownloadsManual And DownloadsDownload the AS502 manual for battery installation, button functions, standard and expert mode selection, operation steps, result reading, maintenance, and warranty information. Click to enlargeAUTOOL AS502 User ManualOpen the PDF manual for setup, brake-fluid type selection, result interpretation, probe maintenance, and warranty details. Download ManualNeed Setup Confirmation?Contact AUTOOL Store before ordering or testing if you need help confirming battery setup, DOT3 / DOT4 / DOT5.1 compatibility, normal or expert mode selection, result reading, or fluid tester model choice.Email[email protected] WhatsApp 86 189 2647 7404 Click to enlargeWhat Is In The BoxWhat Is In The BoxThe packing list image shows the AS502 brake fluid tester, retail box, and user manual. Final package contents should follow the actual product option and package received.Main UnitAUTOOL AS502 brake fluid tester with flexible probeRetail BoxAS502 product packaging shown in the package imageUser ManualAS502 user manual shown in the package imageBattery NoteThe tester uses 4 × 1.5V AAA batteries. Batteries are not shown in the package image; confirm the actual package option before ordering if needed.Questions And AnswersThese answers cover AS502 testing purpose, supported brake fluids, batteries, operation, result reading, maintenance, comparison, and warranty support. What Does AUTOOL AS502 Test? AUTOOL AS502 tests the water content percentage in brake fluid. It helps users evaluate brake fluid condition and decide whether maintenance or replacement may be needed. Which Brake Fluid Types Does AS502 Support? Normal mode supports DOT3, DOT4, and DOT5.1 brake fluid. Expert mode supports selected DOT4 brands, including MOTUL, ATE, FERODO, MOBIL, BREMBO, TRW, BOSCH, CASTROL, TOTAL, VALEO, FUCHS, and TEXTAR. What Batteries Does AS502 Use? AS502 uses 6V power from 4 × 1.5V AAA batteries. Open the rear battery cover, insert the batteries with the correct polarity, and close the cover securely before use. How Do I Use AS502 For A Brake Fluid Test? Clean the probe, open the brake fluid reservoir cap, select the correct brake fluid type or expert-mode brand, immerse the probe into the brake fluid, then press the test button. The screen will display the water content percentage and status indication. How Should I Read The Test Result? The percentage value shows the water content in the brake fluid. OK indicates the water content is good, ! indicates a warning, and × indicates replacement is suggested. The manual describes 0%-2% as a pass range, 2%-3% as a warning range, and above 3% as a replacement range. How Often Should Brake Fluid Be Tested? For routine maintenance, checking brake fluid around every 40,000 km is recommended. Actual testing frequency should also follow the vehicle condition, driving environment, and service requirements. How Should I Maintain The Probe After Use? Wipe the probe clean after use and avoid leaving stains or brake fluid residue on the probe. If the tester will not be used for a long time, remove all batteries and store it in a dry place at normal room temperature. What Is The Difference Between AS502 And Other AUTOOL Fluid Testers? AS502 is for brake fluid water-content testing with a 2.8-inch display, 6V power, and normal/expert modes. AS503 is for engine oil quality, AS505 is for transmission fluid, AS506 is for brake fluid boiling point, and AS507 is for power steering fluid. Choose by the fluid type and test principle you need. How Long Is The Warranty? From the date of receipt, AUTOOL provides a 3-year warranty for the main unit and a 1-year warranty for included accessories. Warranty handling depends on the actual breakdown situation and warranty conditions.Warranty And ContactWarranty And ContactFor AS502 battery setup, brake-fluid compatibility, normal or expert mode selection, result reading, probe maintenance, manual download, package confirmation, warranty support, or model selection, contact AUTOOL Store directly.Pre-Sales And Product SupportUse support if you need help confirming whether AS502 is suitable for your brake fluid type, how to interpret test results, how to maintain the probe, or which AUTOOL fluid tester fits your workshop needs.3-year warranty for the AS502 main unit and 1-year warranty for included accessoriesDOT3 / DOT4 / DOT5.1 and expert-mode brand confirmationBattery installation and power setup helpProbe cleaning and long-term storage guidanceResult reading and replacement-status explanationAS501 / AS502 / AS503 / AS505 / AS506 / AS507 model selection supportEmail Support[email protected] WhatsApp Support 86 189 2647 7404