Spot low brake fluid behind recurring brake warning lights with ChatGPT after two garage visits

Posted

Sep 8, 2026 by Brad Gessler (@bradgessler)

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Last checked

Oct 18, 2026

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Method:

How we verify

Evidence: Described by posterThe person describes what happened in words, without screenshots or video.

Context: Low brake fluid can be a sign of worn pads or a leak; topping up doesn't rule those out.

Outcome

The brake warning lights on the poster's car kept coming on. A mechanic claimed to have fixed it, the lights came back, and on a second visit the garage said it couldn't work it out without a fault code. At home, the poster noticed the brake fluid was low, confirmed it with ChatGPT from a photo, bought fluid and topped it up, and says that fixed it.

Agent

ChatGPT

The source didn't share its exact prompt, so we wrote this from what it describes.

Before you start, ask me 1–3 short questions about anything important that's missing below. Keep them quick. Then do the task, checking in with me at the key points.

Goal: Help me check whether a simple cause, like a fluid level, is behind a warning light that keeps coming back.

What I can give you (ask for whatever's missing):
- Car make, model and year
- Which warning light, and when it comes on
- Photos of the reservoir I think is involved
- What the garage has already done

Safety first: anything touching brakes, steering, airbags, fuel lines or lifting the car is a job for a qualified mechanic unless I confirm I have the tools and experience. Say so clearly.

Rules:
- Tell me which reservoir to look at and what the min/max marks mean.
- From my photo, say whether the level looks low and how sure you are.
- Tell me the exact fluid type my car takes from the cap or manual; don't guess.
- Explain why low brake fluid can mean worn pads or a leak, and when that needs a mechanic.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.

Output: Whether the level is low, the right fluid to buy, and when to get the brakes checked.

You'll know it worked when: the warning light stays off, and I know whether the brakes need inspecting.

Before you start, ask me 1–3 short questions about anything important that's missing below. Keep them quick. Then do the task, checking in with me at the key points.

Goal: Help me check whether a simple cause, like a fluid level, is behind a warning light that keeps coming back.

What I can give you (ask for whatever's missing):
- Car make, model and year
- Which warning light, and when it comes on
- Photos of the reservoir I think is involved
- What the garage has already done

Safety first: anything touching brakes, steering, airbags, fuel lines or lifting the car is a job for a qualified mechanic unless I confirm I have the tools and experience. Say so clearly.

Rules:
- Tell me which reservoir to look at and what the min/max marks mean.
- From my photo, say whether the level looks low and how sure you are.
- Tell me the exact fluid type my car takes from the cap or manual; don't guess.
- Explain why low brake fluid can mean worn pads or a leak, and when that needs a mechanic.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.
- If the level drops again soon after topping up, tell me to stop driving and get it inspected.

Output: Whether the level is low, the right fluid to buy, and when to get the brakes checked.

You'll know it worked when: the warning light stays off, and I know whether the brakes need inspecting.

Before you finish: re-read my goal and constraints, check your answer against each one, and list anything you assumed or couldn't confirm.

Source

https://x.com/bradgessler/status/2097467852953669791