AI Car Diagnostic
Free AI Tool • No Sign-Up Required

Describe Your Symptoms.
Get an Instant Diagnosis.

Type what your car is doing — or paste a code like P0420 — and our AI gives you likely causes, severity, DIY checks, and repair costs in seconds.

⚡Instant results
🔍All P, B, C, U codes
💬Plain English answers
🆓Completely free
// Live Diagnostic Tool
ENGINE ONLINE
PROTOCOL OBD-II / CAN
MODE DIAGNOSTIC
AI CLAUDE
🔌

Ready to Diagnose

Describe your symptoms in plain English, or paste an OBD-II code to get started.

// Common starting points

AI diagnosis is a starting point — always confirm with a proper scan and consult a qualified technician for safety-critical repairs.  |  Browse the Full Code Library →

// How It Works
1
💬

Describe the Problem

Type symptoms in plain English — shaking, smells, warning lights, rough idle — or paste an OBD-II code directly.

2
🧠

AI Analyses It

Our AI cross-references your symptoms against thousands of known OBD-II fault patterns to identify the most likely causes.

3
🔧

Get a Repair Plan

You get ranked causes, a drive/park verdict, first checks to run yourself, and an estimated repair cost range.

4
📚

Go Deeper

Every diagnosis links to our full code library with step-by-step repair guides, freeze frame tips, and scanner advice.

// What Every Diagnosis Includes
🔖

Likely OBD-II Code(s)

The most probable P, B, C, or U codes based on your symptoms, with plain-language descriptions.

📊

Ranked Causes

Up to 5 root causes listed from most to least likely — so you check the right thing first.

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Drive or Park Verdict

A clear Safe / Caution / Do Not Drive recommendation with the reasoning behind it.

🛠️

First DIY Checks

Specific things you can inspect right now before spending a dollar on parts or shop time.

💰

Repair Cost Estimate

Ballpark DIY parts cost vs. shop labor so you know what you’re walking into.

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Follow-Up Conversation

Not satisfied? Ask follow-up questions — the AI remembers your context and digs deeper.

// Frequently Asked Questions
No — you can describe symptoms in plain English without any code at all. If you do have a scanner and a code, paste it in and you’ll get an even more precise diagnosis. Don’t have a scanner yet? See our scanner recommendations →
The AI is highly accurate at identifying the most likely causes based on symptoms and codes. It’s best used as a starting point — always confirm with physical checks before replacing parts. A misfire code, for example, could be plugs, coils, injectors, or a compression issue, and only hands-on testing confirms which.
All standard OBD-II codes: P-codes (powertrain — engine, transmission, emissions), B-codes (body — airbags, HVAC, locks), C-codes (chassis — ABS, traction control), and U-codes (network/module communication). Works on any 1996+ US vehicle. Browse the full code library →
It depends on the fault. A steady light often means a non-urgent issue like a loose gas cap or O2 sensor. A flashing check engine light usually means an active misfire — this can damage your catalytic converter and you should reduce load and diagnose immediately. Describe your situation above and the AI will give you a specific verdict.
Yes, completely free. No sign-up, no account, no limits. Just describe your problem and get an answer.

Need the Full Code Breakdown?

The AI gives you the starting point. The OBD Guides code library gives you the complete step-by-step repair path.

🔍 Browse Code Library 🩺 Diagnose & Fix Guides 🛒 OBD2 Scanner Reviews