ESP32-based CAN bus sniffer that reads all packets from a Renault Clio 3 2012 via OBD2, with decoded output for wheel speed, RPM, and other vehicle data.

Target vehicle: Renault Clio 3 2012 1.2 16V
Purpose: Read odometer and RPM (not available via standard OBD2 PIDs) by sniffing the CAN bus.

Hardware

Component	Model
MCU	ESP32 DOIT DevKit V1
CAN Transceiver	SN65HVD230 VP230 (3.3V)
Connection	OBD2 connector pins 6, 14, GND

Wiring

OBD2 to VP230

OBD2 Pin	Signal	Connect To
6	CAN High	VP230 CAN_H
14	CAN Low	VP230 CAN_L
4 or 5	GND	VP230 GND

VP230 to ESP32

VP230 Pin	ESP32 Pin
TX (or D)	D33 (GPIO 33)
RX (or R)	D32 (GPIO 32)
VCC	3.3V
GND	GND

Diagram

OBD2 Port                    VP230 Module                 ESP32
┌─────────┐                  ┌─────────┐                  ┌─────────┐
│ Pin 6   │──────────────────│ CAN_H   │                  │         │
│ Pin 14  │──────────────────│ CAN_L   │                  │         │
│ Pin 4/5 │──────┬───────────│ GND     │──────────────────│ GND     │
└─────────┘      │           │ TX      │──────────────────│ D33     │
                 │           │ RX      │──────────────────│ D32     │
                 │           │ VCC     │──────────────────│ 3.3V    │
                 └───────────│ GND     │                  └─────────┘
                             └─────────┘

Note: Power the ESP32 via USB. Do not connect OBD2 pin 16 (+12V) to the ESP32.

Build & Upload

pio run -t upload

Usage

Connect hardware as above
Plug into vehicle OBD2 port (under dashboard, driver side)
Turn ignition ON (engine running for full data)
Open serial monitor at 115200 baud

Output Format

Raw frames (all received):

ID:0x29A LEN:7 DATA:00 00 1A 00 00 00 00

Decoded values (when ID is known):

ID:0x29A [WheelSpeed] FL:12.5 km/h FR:12.3 km/h
ID:0x29C [WheelSpeed] RL:12.4 km/h RR:12.6 km/h
ID:0x5D7 [Odometer] 125432 km
ID:0x230 [Engine] RPM: 1850

Decoded CAN IDs (Renault Clio 3 / Megane 3)

ID	Signal	Bytes	Formula
0x29A (666)	Wheel speed front	0-1: FR, 2-3: FL	(byte[1]<<8\|byte[0]) * 0.005 km/h
0x29C (668)	Wheel speed rear	0-1: RR, 2-3: RL	(byte[1]<<8\|byte[0]) * 0.005 km/h
0x5D7	Odometer	2-5	(raw>>4)/100 = km
0x230	Engine RPM (tentative)	2-3	raw/4
0x2D4	Vehicle speed (tentative)	0-1	raw * 0.01 km/h

Odometer (0x5D7): Confirmed on Renault Megane 3 (2010); likely shared with Clio 3. Bytes 2–5 form a 32‑bit value; (raw >> 4) / 100 gives total km. Source: car-reminder.

RPM and odometer IDs may need tuning. If decoded values look wrong:

RPM: Rev the engine and watch which IDs change; adjust ID_ENGINE_RPM and byte/factor in decode_renault()
Odometer: Drive a known distance; find IDs that increment slowly; add a new case in decode_renault()

CAN Bus Speed

500 kbps – Clio 3 main CAN (pins 6/14)
250 kbps – Try if no traffic at 500 kbps (motor diagnostic CAN)

Change CAN_SPEED_KBPS in main.cpp if needed.

README.md Unescape Escape

CAN Bus Reader for Renault Clio 3