Vehicle Compatibility

K-Line supports two distinct protocols that share the same physical layer (single-wire K-line) but target completely different vehicle systems. This page documents which vehicles use which protocol — and when manufacturers transitioned away from K-line to CAN bus.

BMW I-Bus and K-Bus

BMW used I-Bus and K-Bus across their lineup from 1989 through approximately 2013. Both buses use identical signaling (9600 baud, 8E1, XOR checksum) — the difference is which modules are connected to each bus.

• I-Bus (Instrumentation Bus): infotainment — radio, CD changer, navigation, telephone, DSP amplifier
• K-Bus (Body Bus): body control — instrument cluster, light control, climate, door locks, windows, rain sensor

BMW Chassis Compatibility

Chassis	Series	Production	I-Bus	K-Bus	Notes
E31	8 Series	1989–1999	Yes	—	Coupe only, I-Bus for nav/phone
E38	7 Series	1994–2001	Yes	Yes	Both buses, GM5 bridges between them
E39	5 Series	1995–2004	Yes	Yes	Both buses, same architecture as E38
E46	3 Series	1997–2006	—	Yes	K-Bus only, no factory I-Bus
E52	Z8	2000–2003	—	Yes	K-Bus only, shared E39 electronics
E53	X5	1999–2006	Yes	Yes	Both buses
E83	X3	2003–2010	—	Yes	K-Bus only, later models transition to K-CAN
E85/E86	Z4	2002–2008	—	Yes	K-Bus only
E87	1 Series	2004–2013	—	Yes	K-Bus only, late production may use K-CAN

Caution

Late-production E83, E85, and E87 vehicles may have transitioned from K-Bus to K-CAN (a CAN-based body bus). Verify by checking the OBD-II connector pinout — K-Bus uses pin 7 (ISO 9141 K-line), while K-CAN uses pins 6 and 14 (CAN High/Low).

Where I-Bus and K-Bus Connect

On models with both buses (E38, E39, E53), the GM5 body control module acts as a gateway, bridging messages between I-Bus and K-Bus when a module on one bus needs to reach a module on the other.

For models with only K-Bus (E46, E83, E85), all body and infotainment modules share the single bus. The CD changer connector in the trunk is the most accessible tap point — it carries K-Bus, 12V, and ground on a standard connector (X18180 on E46).

Non-BMW Vehicles with I-Bus

Several non-BMW vehicles share the I-Bus protocol due to shared platforms or BMW-sourced electronics:

Make	Model	Years	Platform	Notes
MINI	Cooper / One (R50)	2001–2006	BMW Group	Shared electronics with E46 era
MINI	Cooper S (R53)	2001–2006	BMW Group	Supercharged variant, same bus
MINI	Convertible (R52)	2004–2008	BMW Group	Same bus architecture
Range Rover	L30 (P38A)	1994–2002	BMW era	BMW V8 engine, BMW bus systems
Range Rover	L322	2002–2005	BMW era	Early L322 used BMW electronics (pre-Ford takeover)
Rover	75 / MG ZT	1999–2005	BMW era	Developed under BMW ownership

Note

The Range Rover L322 switched from BMW to Jaguar/Ford electronics around 2005–2006. Only the earlier BMW-era L322s have I-Bus. Check for the BMW-style 20-pin diagnostic connector behind the glovebox — if present, the bus architecture is BMW-derived.

OBD-II K-line (ISO 9141 / ISO 14230)

OBD-II K-line uses ISO 9141-2 (older) or ISO 14230 / KWP2000 (newer) for diagnostic communication. This is a different protocol from BMW I/K-Bus — different baud rate (10400), different checksum (mod256), different bus model (master/slave), and requires an initialization sequence.

In the United States, OBD-II has been mandatory since 1996 for all passenger vehicles and light trucks. The communication protocol was left to the manufacturer’s discretion until 2008, when CAN (ISO 15765) became the sole required protocol.

Protocol Timeline

timeline
    title OBD-II Protocol Evolution
    1996 : OBD-II mandatory (US)
         : Manufacturers choose ISO 9141, KWP2000, J1850, or CAN
    2001 : European OBD (EOBD) mandatory
         : Same protocols, EU emission standards
    2003 : CAN bus begins appearing
         : Manufacturers start transitioning to CAN
    2008 : CAN mandatory (US)
         : All new US vehicles must use ISO 15765 (CAN)
    2014 : CAN mandatory (EOBD)
         : EU catches up, CAN required for all new vehicles

K-line by Manufacturer

The following tables cover which manufacturers used K-line protocols and when they transitioned to CAN. These are general ranges — specific models within a manufacturer may have switched earlier or later.

European

Ford (Europe)

European Fords are completely different from US Fords — they use ISO 9141 / KWP2000 over K-line, not J1850 PWM. This is the primary target for K-Line’s OBD-II mode alongside the Tucker k-line-board project.

Model	Generation	Years	Protocol	Notes
Fiesta	Mk4	1995–2002	ISO 9141-2	Zetec / Endura-DE engines
Fiesta	Mk5	2002–2008	KWP2000	Duratec engines
Focus	Mk1	1998–2004	ISO 9141-2 / KWP2000	Zetec / Duratec
Focus	Mk2	2004–2008	KWP2000	Pre-facelift K-line, facelift models may have CAN
Mondeo	Mk2	1996–2000	ISO 9141-2	Zetec engines
Mondeo	Mk3	2000–2007	KWP2000	Duratec / TDCi
Ka	Mk1	1996–2008	ISO 9141-2	Based on Fiesta Mk4 platform
Puma	—	1997–2001	ISO 9141-2	Zetec-SE engine
Cougar	—	1998–2002	ISO 9141-2 / KWP2000	Based on Mondeo Mk2
C-Max	Mk1	2003–2010	KWP2000	Based on Focus Mk2 platform
Transit	Mk6	2000–2006	KWP2000	Duratorq TDCi
Transit	Mk7	2006–2013	KWP2000	Later models transition to CAN
Galaxy	Mk2	2006–2010	KWP2000	Shared Ford/VW platform

Tip

European Fords sold between 1996 and ~2008 almost universally support K-line. The transition to CAN happened model-by-model — Focus Mk2 facelift (2008+), Fiesta Mk6 (2008+), and Mondeo Mk4 (2007+) were the first CAN-only generations.

Other European Manufacturers

Manufacturer	Protocol	K-line Years	CAN Transition	Key Models
BMW	ISO 9141-2	1996–2006	2005+ (E60, E90)	3/5/7/X5 Series (OBD-II diagnostics separate from I/K-Bus)
Mercedes-Benz	ISO 9141-2 / KWP2000	1996–2004	2004+ (W211, W203 FL)	C-Class (W202/W203), E-Class (W210/W211), ML (W163)
Volkswagen	KWP2000	1996–2004	2004+ (Golf V)	Golf IV, Passat B5, Polo 9N, Bora/Jetta IV
Audi	KWP2000	1996–2004	2004+ (B7 A4)	A3 (8L), A4 (B5/B6), A6 (C5), TT (8N)
Porsche	ISO 9141-2	1996–2004	2005+ (997)	911 (996), Boxster (986), Cayenne (955)
Volvo	KWP2000	1996–2004	2005+ (V50, S40 gen 2)	S60, V70, S80, XC70, XC90 (P2 platform)
Saab	KWP2000	1996–2002	2003+ (9-3 gen 2)	9-3 gen 1, 9-5
Fiat / Alfa Romeo	ISO 9141-2	1996–2005	2005+	Punto, Stilo, 156, 147, Doblo
Peugeot / Citroen	ISO 9141-2 / KWP2000	1996–2004	2004+	206, 306, 307, Xsara, C3, C4
Renault	ISO 9141-2	1996–2004	2005+	Clio II, Megane I/II, Scenic, Laguna
Opel / Vauxhall	KWP2000	1996–2004	2004+ (Astra H)	Corsa C, Astra G, Vectra B/C, Zafira A
SEAT	KWP2000	1996–2004	2004+	Ibiza III, Leon I, Toledo II (VW platform)
Skoda	KWP2000	1996–2004	2004+	Fabia I, Octavia I, Superb I (VW platform)

Japanese

Honda

One of the last K-line holdouts — many Honda models used ISO 9141-2 right up until the 2008 US CAN mandate.

Model	Years (K-line)	Protocol	Notes
Civic	1996–2005	ISO 9141-2	7th gen (2001-2005) last K-line Civic
Accord	1996–2007	ISO 9141-2	7th gen (2003-2007) one of the last K-line Hondas
CR-V	1997–2006	ISO 9141-2	1st gen (1997-2001) and 2nd gen (2002-2006)
Odyssey	1999–2005	ISO 9141-2	2nd gen (1999-2004)
Element	2003–2007	ISO 9141-2	All model years
S2000	1999–2009	ISO 9141-2	K-line for entire production run
Fit / Jazz	2001–2007	ISO 9141-2	1st gen
Integra / RSX	1996–2006	ISO 9141-2
Prelude	1996–2001	ISO 9141-2	All OBD-II Preludes

Toyota / Lexus

Toyota used KWP2000 (ISO 14230) — the newer K-line variant with fast init support.

Model	Years (K-line)	Protocol	Notes
Corolla	1996–2006	KWP2000	9th gen (2000-2006) last K-line Corolla
Camry	1996–2006	KWP2000	XV30 (2002-2006) last K-line Camry
RAV4	1996–2005	KWP2000	XA20 (2000-2005)
Highlander	2001–2007	KWP2000	1st gen
4Runner	1996–2005	KWP2000	N180 (1996-2002) and early N210
Tacoma	1996–2004	KWP2000	1st gen
Land Cruiser	1996–2005	KWP2000	J100
Yaris / Echo	1999–2005	KWP2000	XP10
Celica	1996–2006	KWP2000	T230 (2000-2006)
MR2 Spyder	1999–2007	KWP2000	ZZW30
Lexus IS 300	2001–2005	KWP2000	XE10
Lexus GS 300	1998–2005	KWP2000	S160
Lexus RX 300	1999–2003	KWP2000	XU10

Nissan / Infiniti

Model	Years (K-line)	Protocol	Notes
Altima	1996–2006	ISO 9141-2	L31 (2002-2006) last K-line Altima
Sentra	1996–2006	ISO 9141-2	B15 (2000-2006)
Maxima	1996–2004	ISO 9141-2	A33 (2000-2003)
Pathfinder	1996–2004	ISO 9141-2	R50
Frontier	1998–2004	ISO 9141-2	D22
Xterra	2000–2004	ISO 9141-2	WD22
350Z	2003–2006	ISO 9141-2	Z33 (early production)
Infiniti G35	2003–2006	ISO 9141-2	V35
Infiniti QX4	1997–2003	ISO 9141-2

Mazda

Model	Years (K-line)	Protocol	Notes
Protege / 323	1996–2003	ISO 9141-2	BJ
Mazda3	2004–2006	ISO 9141-2	BK, pre-facelift
Mazda6	2003–2005	ISO 9141-2	GG, 1st gen early
MX-5 / Miata	1996–2005	ISO 9141-2	NB (1998-2005)
MPV	1996–2006	ISO 9141-2	LW
RX-8	2004–2005	ISO 9141-2	SE3P, early production
Tribute	2001–2006	ISO 9141-2	EP, Ford Escape platform

Subaru

Model	Years (K-line)	Protocol	Notes
Impreza / WRX	1996–2004	ISO 9141-2	GD/GG (2001-2004)
Legacy / Outback	1996–2004	ISO 9141-2	BE/BH (1999-2003) last K-line gen
Forester	1998–2004	ISO 9141-2	SG (2003-2004)
Baja	2003–2006	ISO 9141-2

Mitsubishi

Model	Years (K-line)	Protocol	Notes
Lancer / Evo	1996–2006	ISO 9141-2	CT9A Evo VII-IX
Eclipse	1996–2005	ISO 9141-2	3G (2000-2005)
Outlander	2003–2006	ISO 9141-2	CU, 1st gen
Galant	1996–2006	ISO 9141-2	8th gen (1996-2004)
Montero / Pajero	1996–2006	ISO 9141-2	V60/V70

Korean

Hyundai

Model	Years (K-line)	Protocol	Notes
Elantra	1996–2006	KWP2000	XD (2001-2006)
Sonata	1996–2005	KWP2000 / ISO 9141	EF (1998-2005), NF switched to CAN
Santa Fe	2001–2006	KWP2000	SM, 1st gen
Tucson	2004–2009	KWP2000	JM
Accent	1996–2005	KWP2000 / ISO 9141	LC (2000-2005)
Tiburon / Coupe	1996–2008	KWP2000	GK (2003-2008)

Kia

Model	Years (K-line)	Protocol	Notes
Optima	2001–2005	KWP2000	MS, 1st gen
Sorento	2003–2006	KWP2000	BL, 1st gen
Sportage	2005–2008	KWP2000	JE, 2nd gen
Spectra / Cerato	2001–2006	KWP2000	LD
Rio	2001–2005	KWP2000	DC, 1st gen
Carnival / Sedona	1998–2005	KWP2000

Suzuki

Model	Years (K-line)	Protocol	Notes
Swift	1996–2006	KWP2000	HT51S / ZC31S
Grand Vitara	1998–2005	KWP2000	FT/GT
SX4	2006–2009	KWP2000	GY, late K-line model
Jimny	1998–2007	KWP2000	JB23/JB33
Liana / Aerio	2001–2007	KWP2000

American

Chrysler / Dodge / Jeep

Chrysler used ISO 9141-2 almost exclusively for OBD-II diagnostics before the 2008 CAN mandate — making them the most common K-line vehicles on US roads.

Model	Years (K-line)	Protocol	Notes
Jeep Wrangler	1996–2006	ISO 9141-2	TJ
Jeep Cherokee	1996–2001	ISO 9141-2	XJ
Jeep Grand Cherokee	1996–2004	ISO 9141-2	WJ (1999-2004)
Dodge Ram	1996–2007	ISO 9141-2	3rd gen (2002-2008, pre-CAN)
Dodge Neon	1996–2005	ISO 9141-2
Dodge Caravan	1996–2007	ISO 9141-2	RS (2001-2007)
Chrysler PT Cruiser	2001–2010	ISO 9141-2
Chrysler 300M	1999–2004	ISO 9141-2	LH platform
Dodge Dakota	1996–2004	ISO 9141-2	AN (1997-2004)
Dodge Durango	1998–2003	ISO 9141-2	DN

Ford (US Market)

US-market Fords used J1850 PWM — a different protocol that K-Line does not support. Pin 2 on the OBD-II connector instead of pin 7.

Caution

European Fords are different! Ford Fiesta, Focus, Mondeo, Ka, Transit, and other European-market Fords use ISO 9141 / KWP2000 over K-line. See the European tab for model-level detail. US-market Fords used J1850 PWM instead.

A handful of US Ford-badged vehicles did use K-line because they had non-Ford engines:

Model	Years	Protocol	Why K-line?
Escort 1.8L	1996	ISO 9141	Mazda BP engine
Probe	1996–1997	ISO 9141	Mazda MX-6 platform
Aspire	1996–1997	ISO 9141	Kia/Mazda platform
Mercury Villager	1996–1998	ISO 9141	Nissan VG30E engine

GM (US Market)

US-market GM vehicles used J1850 VPW — also not K-line. Pin 10 on the OBD-II connector.

Note

GM exceptions: Some 2005–2007 GM vehicles added KWP2000 (ISO 14230) alongside CAN during the transition period. European GM vehicles (Opel/Vauxhall) used K-line — see the European tab.

Identifying Your Vehicle’s Protocol

The OBD-II connector pinout tells you which protocol(s) your vehicle supports. Check which pins are populated:

Pin	Protocol	Signal
2	J1850 PWM (Ford)	Bus+
4	Chassis ground	GND
5	Signal ground	GND
6	CAN bus	CAN High
7	ISO 9141 / ISO 14230 (K-line)	K-line
10	J1850 VPW (GM)	Bus
14	CAN bus	CAN Low
15	ISO 9141 / ISO 14230 (optional)	L-line
16	Battery positive	+12V

If pin 7 is populated and pins 6/14 are not, the vehicle uses K-line exclusively — this is the target for K-Line’s OBD-II mode.

If pin 7 AND pins 6/14 are populated, the vehicle supports both K-line and CAN. The ECU may respond on either protocol, but CAN is generally preferred by modern scan tools. K-Line can still use the K-line path.

If only pins 6/14 are populated (no pin 7), the vehicle is CAN-only and cannot be reached via K-line.

Tip

A multimeter or continuity tester on the OBD-II connector is the definitive way to determine protocol support. Pin 7 should show approximately battery voltage (12V) at key-on if K-line is active — the bus idles HIGH.

Protocol Coverage Summary

Protocol	Interface	Use Case	Vehicle Count
BMW I/K-Bus	Optocoupler (PC817)	Body/infotainment control	~15 BMW/MINI/Rover models (1989–2013)
OBD-II K-line	Optocoupler or transistor	Engine diagnostics (ISO 9141/14230)	Hundreds of models (1996–2008)
OBD-II CAN	Not supported (different physical layer)	—	All vehicles 2008+

The optocoupler circuit in this project was designed for BMW I/K-Bus but works for OBD-II K-line as well — both protocols use the same electrical signaling (open-drain/collector on a single wire, idle HIGH). The K-Line firmware handles the protocol differences (baud rate, framing, checksum, initialization) in software.

References

• muki01/OBD2_K-line_Reader — Arduino/ESP32 K-line reader supporting ISO 9141 and ISO 14230 with automatic protocol detection. Includes transistor, comparator (LM393), and dedicated IC (L9637D, MCZ33290, SN65HVDA195) schematics.
• muki01/I-K_Bus — BMW I/K-Bus library that K-Line’s protocol handler is based on. Optocoupler schematic, E46 command codes, and bus documentation.
• SAE J1979 — OBD-II PID definitions and decode formulas (Mode 01 current data).
• ISO 9141-2 — K-line 5-baud slow initialization protocol.
• ISO 14230-4 (KWP2000) — K-line fast initialization and enhanced diagnostic services.