Screen Brake Fluid Moisture Straight From the Reservoir
Dip the AS502’s flexible probe into the reservoir and read the water content with an OK, warning or replace indicator. Normal mode covers DOT3, DOT4 and DOT5.1; expert mode adds references for selected DOT4 brands. Brake fluid only.
- DOT3 / DOT4 / DOT5.1
- Normal + Expert Modes
- 260 mm Flexible Probe
- 2.8-Inch Backlit LCD
- 4 × AAA Power
Key Features
-
Water-Content Screening
Measures the water percentage in brake fluid for quick condition checks. It does not generate or measure hydraulic brake pressure.
-
Normal and Expert Modes
Choose a standard fluid type, or switch to expert mode for more targeted selection by DOT4 brand.
-
Reservoir-Reach Probe
The gooseneck probe bends into the reservoir; its stainless steel outer layer resists oil, oxidation and corrosion.
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Clear Status Indicators
OK means the water content is good, ! is a warning and × suggests replacement, shown beside the percentage.
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Single-Handed Use
A silicone grip and handheld button layout let you test with one hand.
-
Battery Saving
Switches itself off when left idle.
AS502 vs AS501
| AS502 | AS501 | |
|---|---|---|
| Display | 2.8-inch backlit | 1.8-inch backlit |
| Test modes | Normal / Expert | Normal |
| Normal-mode fluids | DOT3, DOT4, DOT5.1 | ENV-4, ENV-6, DOT3, DOT4, DOT5, DOT5.1 |
| Power supply | 6 V | 3 V |
| Probe hose material | 304 stainless steel | Iron oxide |
What’s in the Box
- AS502 brake fluid tester with flexible probe
- User manual
How to Use
- Install batteriesOpen the rear cover, insert four AAA batteries with correct polarity and close the cover securely.
- Power onHold the power button for more than 2 seconds.
- Clean the probeWipe the probe before each measurement so residue does not affect the result.
- Open the reservoirRemove the brake fluid reservoir cap.
- Select the fluidPress the selection button to choose DOT3, DOT4, DOT5.1 or an expert-mode DOT4 brand.
- Immerse and testSubmerge the probe, press the test button and read the water percentage and status.
Modes, result interpretation and troubleshooting: AS502 user manual (PDF).
Good to Know
Caution
- For brake fluid only; it is not an engine oil, transmission fluid or power steering fluid tester.
- Batteries may not be included; confirm with your package before ordering.
Care
- The reading is a moisture screening, not a standardized wet boiling-point result; apply it with the vehicle’s service criteria.
- For routine maintenance, checking brake fluid around every 40,000 km is suggested, depending on vehicle condition.
- Wipe the probe clean after use and leave no fluid residue on it.
- For long storage, remove all batteries and keep the tester dry at room temperature.
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