Your check engine light is data. OBDecode decodes it instantly, cross-referencing TSB records, NHTSA recalls, and pattern failures for your exact vehicle — the depth a shop charges $150 just to look up.
01
Enter Your Vehicle
VIN or manual entry — year, make, model, engine, mileage. Tap the camera icon to scan your VIN barcode. The more context, the sharper the result.
02
Add Codes & Symptoms
Describe what the vehicle is doing and when. Add fault codes. OBDecode cross-references TSBs and may ask follow-up questions to sharpen diagnosis before showing fixes with full repair steps.
03
Get Your Report
Technical briefing, diagnostic flowchart, probable fixes with step-by-step repair instructions, NHTSA recall check, and PDF export — depth a shop charges for, in seconds.
⬡ RECENT DIAGNOSES▼
⬡ Vehicle Configuration Matrix
CORROSION INDEX
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⬡ READY — CONNECT YOUR OBD ADAPTER
BETA
⬡ STORED FAULT CODES
⬡ PENDING CODES
⬡ FREEZE FRAME — CONDITIONS WHEN CODE SET
⬡ LIVE SENSOR DATA
ENGINE RPM
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SPEED km/h
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COOLANT °C
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LOAD %
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THROTTLE %
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BATTERY V
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STFT B1 %
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LTFT B1 %
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MAF g/s
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⬡ READINESS MONITORS — EMISSIONS / INSPECTION
Feeds codes · freeze frame · sensor readings · monitors into the AI engine
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A few quick questions
TO IMPROVE DIAGNOSTIC ACCURACY
Cross-referencing TSB database...
0%
AUTHENTICATING VEHICLE PROFILE...
ANALYZING FAULT SIGNATURE MATRIX...
CROSS-REFERENCING FAILURE PATTERNS...
MODELING REPAIR PROBABILITY TREE...
COMPILING TARGETED REPAIR PLAN...
⚠ CONNECTION FAULT DETECTED
⬡ Technical Briefing
⬡ Most Probable Fixes
TAP ANY CARD BELOW FOR STEP-BY-STEP REPAIR INSTRUCTIONS
⬡ RETRIEVING REPAIR PROCEDURE...
⬡ Corrosion Labor Factor
⬡ No-Scanner Code Retrieval
⬡ Diagnostic Flowchart
⬡ Targeted Solutions & Components
⬡ Recommended Resources
⬡ SEARCHING FORUMS & MANUALS...
No results found for this vehicle configuration.
⚠ Active NHTSA Safety Recalls
⬡ NHTSA Owner Complaints
⬡ Maintenance Due at This Mileage
GENERATING MAINTENANCE SCHEDULE...
⬡ Supplemental Analysis
Input additional findings, test results, or updated symptoms for a targeted second-pass analysis.
⬡ Refined Diagnosis
⬡ Was this diagnosis helpful?
Rate the quality of your results
Any additional feedback? (optional)
0 / 500
✓ THANK YOU — YOUR FEEDBACK HELPS IMPROVE THE TOOL
⬡ Why OBDecode
TSB + Pattern Failure Cross-Reference
Not a code dictionary. Every diagnosis is run against Technical Service Bulletins and real-world pattern failures for your exact year, make, model, and engine configuration.
Diagnostic Flowcharts
Step-by-step visual decision trees tailored to your fault codes and symptoms. Follow the exact test sequence a technician would run — from initial check to confirmed repair.
Live OBD Scanner Built In
Real-time sensor data via Bluetooth ELM327. Monitor RPM, speed, coolant temp, fuel trims, O2 sensors, and 40+ live PIDs — with bi-directional control for advanced tests.
Free. No Account. No App.
Works in any browser. No download, no login, no subscription required. The full diagnostic engine is free — because everyone deserves to know what's actually wrong with their vehicle.
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Built by Ian Littlefield
Independent Developer · Automotive Enthusiast
"I built OBDecode because I was tired of paying shops $150 just to tell me what my scanner already knew. Every feature in this tool came from real diagnostic frustration. The core engine is free to use right now — Pro features are on the way."
Professional OBD2 Diagnostic & AI Research
OBDecode is a free professional diagnostic platform for technicians, enthusiasts, and everyday drivers. Enter your vehicle details and symptoms for AI-powered diagnosis cross-referenced against TSB databases, NHTSA records, and real-world pattern failures — or connect your ELM327 Bluetooth adapter for live sensor monitoring.
TSB Cross-Reference
Every diagnosis is cross-referenced against Technical Service Bulletins and manufacturer pattern failure records for your specific vehicle configuration and platform. Not guesses — documented failures.
Diagnostic Flowcharts
Step-by-step visual decision trees tailored to your fault codes and symptoms — from the first test to confirmed repair. Follow the same diagnostic sequence a master tech would run.
Component Priority List
Ranked list of components to inspect and test, ordered by diagnostic priority for your specific vehicle platform and reported symptoms. Know what to check first — and what to skip.
No-Scanner Code Retrieval
Retrieve DTCs on supported vehicles without an OBD2 scanner — including Chrysler key dance, GM ALDL blink codes, and Ford self-test procedures. Diagnose from the driver's seat.
NHTSA Recall & Complaint Lookup
Every diagnosis checks active federal safety recalls and owner complaint patterns from the NHTSA database for your exact vehicle. Know if your issue is already documented at the federal level.
Live OBD2 Scanner
Connect your ELM327 Bluetooth adapter for real-time sensor monitoring, bi-directional control tests, and live PIDs. Freeze frame data, monitor readiness status, and clear codes directly from the browser.
Supports all makes including Ford, Chevrolet, Dodge, Toyota, Honda, Jeep, Nissan, Subaru, BMW, Audi, and more. Works with OBD1 and OBD2 vehicles from 1980 to present. No account required. The full diagnostic engine is available now — Pro features including multi-vehicle garage, PDF report export, and expert consultations are in development.
Connect your ELM327 BLE adapter, then tap SCAN. The engine reads stored DTCs, pending codes, freeze frame data, and readiness monitors — all in one pass. Tap DEEP AI DIAGNOSIS to send everything to the AI engine.
VIN DECODED
Pair your ELM327 BLE adapter · Any OBD-II port (2001+) · Web Bluetooth required
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STORED DTC
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PENDING DTC
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MON FAIL
VEHICLE HEALTH SCORE—
BATTERY VOLTAGE—
⬡ AI DEEP DIAGNOSIS
Send all scan data to OBDecode AI engine for repair flowchart, TSB lookup, and root-cause analysis with part numbers
⬡ AI MONITORING PLAN — LOG THESE PARAMETERS
OBDecode identified these as key parameters to capture during your next drive cycle:
Highlighted in gold on LIVE tab. Relevant PIDs auto-selected.
⬡
LIVE DATA TAB
Real-time sensor readings from the ECU — RPM, coolant temp, throttle, MAF, fuel trims, and more. Switch between GAUGES (dial tiles), LIST (all PIDs, tap to pin to gauges), and GRAPH (time-series plot). Select PIDs in LIST view before recording with the data logger in TOOLS.
CONNECT TO START LIVE DATA
SELECT PIDs IN LIST VIEW · TAP GAUGE TO REMOVE
0 SELECTED
IDLE
SELECT PIDs IN LIST TAB · THEN TAP REC
— NO DATA —
⬡ SESSION STATS
LOGS ACTIVE PIDs WITH TIMESTAMPS · EXPORT CSV FOR TUNING / DYNO ANALYSIS
⬡
FAULT CODES TAB
Stored codes (Mode 03) are confirmed faults that turned on the MIL. Pending codes (Mode 07) are maturing — seen once but not confirmed. Tap a DTC to get its definition. Use AI DIAGNOSIS → to send all codes to the deep research engine. Clear codes only after diagnosis and repair.
⬡ STORED FAULT CODES
NO SCAN DATA — CONNECT AND SCAN
⬡ PENDING CODES
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⬡
FREEZE FRAME TAB
The ECU captures a snapshot of sensor values at the exact moment a fault code is set. This freeze frame is your most important clue — it shows what RPM, load, coolant temp, and throttle position were when the fault occurred. Cross-reference with your DTC for accurate root cause analysis.
⬡ FREEZE FRAME — CONDITIONS WHEN CODE SET
FREEZE FRAME CAPTURED WHEN CODES ARE READ
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READINESS TAB
Readiness monitors show whether the ECU has run each emissions self-test since the last code clear. All monitors must show COMPLETE to pass a smog/emissions inspection. After clearing codes, complete a full drive cycle to reset them — typically highway and city driving at varied speeds.
⬡ READINESS MONITORS — EMISSIONS / INSPECTION STATUS
✓ COMPLETE = monitor has run and passed
✗ INCOMPLETE = monitor has not run since last code clear
All monitors must be complete to pass emissions inspection.
READINESS DATA LOADED AFTER FULL SCAN
⬡
BI-DIRECTIONAL TAB
Send commands directly to the ECU to activate actuators, read/write data identifiers (DIDs), sweep for hidden DTCs, and run Mode 06 EVAP tests. Always enter a UDS session before sending commands. Pre-CAN vehicles (J1850 PWM) use the Ford EEC self-test panel instead.
⬡ BIDIR AVAILABLE — MODULE SCAN RECOMMENDED
⬡ BI-DIRECTIONAL CONTROL
Sends commands directly to the ECU to activate actuators, read/write data identifiers (DIDs), sweep for hidden DTCs, and run Mode 06 EVAP tests. These are professional-level tools — an incorrect write can disable safety systems. Always note the original value before writing and do not power off the vehicle mid-write.
⚠ ADVANCED — SENDS COMMANDS TO ECU. WRONG SETTINGS CAN DISABLE SAFETY SYSTEMS.
ALWAYS BACKUP ORIGINAL VALUE BEFORE WRITING. DO NOT POWER OFF DURING WRITE.
⬡ J1850 PWM DETECTED — UDS NOT AVAILABLE ON PRE-CAN VEHICLES.
USE EEC SELF-TESTS BELOW. STANDARD OBD-II (DTCs, LIVE DATA) WORKS NORMALLY.
FORD EEC SELF-TEST (MODE 08)
SCP MODULE SCAN (J1850 PWM)
TARGET MODULE
NO SESSION
CONNECT ADAPTER THEN ENTER SESSION
TAP TO ACTIVATE · TAP AGAIN TO STOP · MAKE-SPECIFIC COMMANDS LOADED FROM VEHICLE INFO
FACTORY-PROGRAMMED ECU SEQUENCES — RUNS FULL ROUTINE THEN READS RESULT
QUICK READ
READ CURRENT VALUE FIRST — ORIGINAL IS BACKED UP AUTOMATICALLY BEFORE ANY WRITE
SCANS EVERY KNOWN MODULE FOR STORED DTCs · UDS SERVICE 0x19 02 08 (BY STATUS MASK) · OBD MODE 03 FOR FALLBACK
ON-BOARD MONITOR TEST RESULTS · RAW VALUE vs PASS/FAIL THRESHOLD · CATALYST · O2 · EVAP · MISFIRE · EGR · SECONDARY AIR
SECURITY ACCESS GATES DEALER-LEVEL FUNCTIONS · KEY ALGORITHM IS MANUFACTURER-SPECIFIC · MANY OLDER VW/GM ARE PUBLIC
All OBD mode commands, settings (units, poll rate, wake lock), debug log export, sensor data recorder, vehicle info, and community sensor reference.
⬡ VEHICLE INFORMATION
VIN—
YEAR—
MAKE—
MODEL—
ENGINE—
OBD PROTOCOL—
ADAPTER—
LAST SCAN—
⬡ PERFORMANCE TIMER
0.00s
0–60 MPH / 0–100 KM/H
IDLE — CONNECT & DRIVE TO USE
PERFORMANCE LAB ↗
0–60 TIMER · G-FORCE METER · HP ESTIMATOR · RUN HISTORY
›
⬡ HUD MODE
HEADS-UP DISPLAY
MIRROR DISPLAY FOR WINDSHIELD REFLECTION
⬡ REPORT
NO HISTORY YET
⬡ OBD TERMINAL
⬡ DTC CODE LOOKUP
⬡ OBD MODE COMMANDS
Send raw OBD-II mode commands to the ECU. Mode 01 = live sensor data, 02 = freeze frame PIDs, 03 = stored DTCs, 04 = clear codes, 05 = O2 sensor test results (non-CAN), 07 = pending DTCs, 09 = vehicle info (VIN, calibration IDs), 0A = permanent/emission-related DTCs. Results appear in the debug log.
⬡ SETTINGS
Units, poll rate, and connection behavior. FAST poll (200ms) gives the smoothest live data but consumes more BLE bandwidth — use NORM or SLOW on older adapters that can't keep up. Wake Lock prevents the screen from sleeping while connected, useful when monitoring during a test drive.
TEMPERATURE UNITS
COOLANT, INTAKE AIR, CATALYST
SPEED UNITS
VEHICLE SPEED
AUTO-RECONNECT
RECONNECT ON BLE DROP
POLL RATE
LIVE SENSOR REFRESH
WAKE LOCK
KEEP SCREEN ON WHEN CONNECTED
⬡ DEBUG LOG
Logs every raw ELM327 command and response. Enable before reproducing a connection problem, then DOWNLOAD .TXT and share the log file when reporting adapter issues. The log shows exactly what the ECU said — including any error frames (UNABLE TO CONNECT, NO DATA, BUS BUSY) that indicate communication problems.
ENABLE DEBUG LOGGING
LOGS ALL RAW ELM327 TRAFFIC & PARSED VALUES
⬡ DATA LOGGER
Records timestamped PID values to CSV for ECU tuning and performance analysis. First go to LIVE → LIST tab and check the PIDs you want to record. Then return here and tap REC ●. Tap STOP when done, then DOWNLOAD CSV. Open the CSV in Excel or TunerPro for analysis.
SENSOR RECORDING
IDLE — CONNECT TO START
LOGS ACTIVE LIVE PIDS AS TIMESTAMPED CSV · SELECT PIDS IN LIVE→LIST TAB BEFORE RECORDING · FOR ECU TUNING & DYNO ANALYSIS
iOS 13+ requires explicit permission for accelerometer
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TIME
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PEAK G
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TOP SPEED
⬡ OBD SPEED USED AUTOMATICALLY IF SCANNER TAB IS OPEN
⬡ DEVICE ACCELEROMETER USED AS FALLBACK — MOUNT PHONE FLAT
⬡ LAUNCH DETECT: LONG-G > 0.15 OR SPEED > 3 MPH
⬡ MOUNT IN LANDSCAPE ON DASH · SCREEN FACING DRIVER
0.00
LONG G
0.00
LAT G
0.00
COMBINED
0.00g
PEAK ACCEL
0.00g
PEAK BRAKE
0.00g
PEAK LAT
MOUNT PHONE FLAT ON DASH · SCREEN UP · CALIBRATE ZERO BEFORE DRIVING
RING = 1G · OUTER EDGE = 1.5G · DOT = CURRENT VECTOR · TRACE = LAST 3s
VEHICLE WEIGHT
CURB WEIGHT + FUEL + DRIVER. CURB WEIGHT IS USUALLY 10–15% UNDER TOTAL.
ARMS TIMER AUTOMATICALLY · ACCELERATE HARD FROM STANDSTILL TO TOP SPEED OR REV LIMIT
ESTIMATED WHEEL HORSEPOWER
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WHEEL HP (ESTIMATED)
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LB-FT TORQUE
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SPEED @ PEAK HP
⚠ WHEEL HP ESTIMATE ±15–25% · EXCLUDES DRIVETRAIN EFFICIENCY VARIATION, AIR DENSITY,
ALTITUDE, AND SURFACE CONDITIONS. FOR REFERENCE AND TREND TRACKING ONLY — NOT A DYNO.