OBD

OBD (sigla do inglês On-Board Diagnostic: "diagnóstico a bordo") e OBD-II, é um sistema eletrônico de autodiagnóstico de veículos; um recurso integrado ao computador de bordo na maioria dos automóveis que circulam atualmente, telemática e IoT.^[1] As informações são geradas pelas unidades de controle do motor (ECU ou módulos de controle).^[1]

A conexão ao sistema consiste em um conector padronizado que foi sancionado como obrigatório na Europa e nos Estados Unidos para todos os veículos produzidos desde 1996, e no Brasil a partir de 2010 com o padrão de segunda geração OBD2 (ou ODBII). A porta OBD-II pode ter uma configuração de 6, 9, à 16 pinos.^[1]

A medida tem a finalidade de popularizar o serviço de reparo eletrônico, reduzindo drasticamente o custo das oficinas, possibilitando o consumidor pagar mais barato por esse gênero de serviço. Além disso, a padronização e abertura dos protocolos de comunicação trouxeram ao mercado equipamentos extremamente baratos possibilitando a compra dos mesmos pelos próprios consumidores para "diagnóstico em casa". Atualmente existem no mercado equipamentos de diagnóstico na ordem de $20 dólares com interface USB e tecnologia Bluetooth para sincronização com um computador ou aparelho celular.

Versões

O OBD-II é a segunda geração do OBD, este era inicialmente conectado externamente ao console do carro, enquanto o OBDII é integrado dentro do veículo.^[1]

EOBD (sigla do inglês European On-Board Diagnostics, onde os automóveis a gasolina fabricados na Europa a partir de 2001 e os diesel desde 2003 devem ter sistemas de diagnóstico a bordo para monitorizar as emissões do motor.^[2]

WWH-OBD (sigla do inglês World wide harmonized on-board diagnostics: "diagnóstico a bordo harmonizado a nível mundial") é padrão internacional usado para o diagnóstico de veículos implementada pela ONU, devido o mandato do Regulamento Técnico Global (GTR), este usa os Serviços Unificados de Diagnóstico (do inglês Unified Diagnostic Services, UDS) com Códigos de Diagnóstico de Problemas (do inglês Diagnostic Trouble Codes, DTC) de 3 bytes.^[1]

História

A ideia de diagnóstico a bordo é da década de 1960, quando várias organizações fizeram as bases para um padrão, como a California Air Resources Board (CARB), a Society of Automotive Engineers (SAE), a International Organization for Standardization (ISO) e a Environmental Protection Agency (EPA).^[1]

Assim em 1968 a Volkswagen lançou o primeiro sistema de computador OBD com capacidade de digitalização do diagnóstico.^[1] Em 1979 a Society of Automotive Engineers recomenda um conector padronizado e um conjunto de sinais de teste DTC.^[1]

Informações

O OBDII tem acesso às informações de status e aos códigos DTC:^[1]

• Veículos (motor e transmissão)
• Controle de Emissões

• Identificação do veículo
• Identificação da Calibração
• Contador de ignição Modo 1: informação do veículo^[1]

• Pid 12: RPM do motor
• Pid 13: Velocidade do veículo

Modo 3: problemas (P = Powertrain, C = Chassis, B = Body, U = Network)^[1]

• P0201: avaria no circuito do injetor – cilindro 1
• P0217: temperatura do motor
• P0219: excesso de velocidade
• C0128: fluido de freio baixo
• C0710: avaria na posição do volante
• B1671: módulo de bateria de tensão fora de alcance
• U2021: dados inválidos

WWH UDS^[1]

• P0070: temperatura do ar ambiente
• P0071: desempenho dos sensores de temperatura do ambiente
• P0072: pouca entrada no circuito do sensor de temperatura
• P0073: muita entrada no circuito do sensor de temperatura
• P0074: entrada intermitente no circuito do sensor de temperatura

Service 01 - dados atuais

PID (hex)	PID (Dec)	Dado retornado	Descrição	Min valor	Max valor	Unit	Formula[a]
00	0	4	PIDs suportado [$01 - $20]				Bit encoded [A7..D0] == [PID $01..PID $20] See below
01	1	4	Monitor status since DTCs cleared. (Includes malfunction indicator lamp (MIL), status and number of DTCs, components tests, DTC readiness checks)				Bit encoded. See below
02	2	2	DTC that caused freeze frame to be stored.				Decoded as in service 3
03	3	2	Fuel system status				Bit encoded. See below
04	4	1	Calculated engine load	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$ (or ${\displaystyle {\tfrac {A}{2.55}}}$)
05	5	1	Engine coolant temperature	-40	215	°C	${\displaystyle A-40}$
06	6	1	Short term fuel trim (STFT)—Bank 1	-100 (Reduce Fuel: Too Rich)	99.2 (Add Fuel: Too Lean)	%	$${\displaystyle {\frac {100}{128}}A-100}$$(or ${\displaystyle {\tfrac {A}{1.28}}-100}$ )
07	7	1	Long term fuel trim (LTFT)—Bank 1
08	8	1	Short term fuel trim (STFT)—Bank 2
09	9	1	Long term fuel trim (LTFT)—Bank 2
0A	10	1	Fuel pressure (gauge pressure)	0	765	kPa	${\displaystyle 3A}$
0B	11	1	Intake manifold absolute pressure	0	255	kPa	${\displaystyle A}$
0C	12	2	Engine speed	0	16,383.75	rpm	${\displaystyle {\frac {256A+B}{4}}}$
0D	13	1	Vehicle speed	0	255	km/h	${\displaystyle A}$
0E	14	1	Timing advance	-64	63.5	° before TDC	${\displaystyle {\frac {A}{2}}-64}$
0F	15	1	Intake air temperature	-40	215	°C	${\displaystyle A-40}$
10	16	2	Mass air flow sensor (MAF) air flow rate	0	655.35	g/s	${\displaystyle {\frac {256A+B}{100}}}$
11	17	1	Throttle position	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$
12	18	1	Commanded secondary air status				Bit encoded. See below
13	19	1	Oxygen sensors present (in 2 banks)				[A0..A3] == Bank 1, Sensors 1-4. [A4..A7] == Bank 2...
14	20	2	Oxygen Sensor 1 A: Voltage B: Short term fuel trim	0 -100	1.275 99.2	V %	$${\displaystyle {\frac {A}{200}}}$$$${\displaystyle {\frac {100}{128}}B-100}$$(if B==$FF, sensor is not used in trim calculation)
15	21	2	Oxygen Sensor 2 A: Voltage B: Short term fuel trim
16	22	2	Oxygen Sensor 3 A: Voltage B: Short term fuel trim
17	23	2	Oxygen Sensor 4 A: Voltage B: Short term fuel trim
18	24	2	Oxygen Sensor 5 A: Voltage B: Short term fuel trim
19	25	2	Oxygen Sensor 6 A: Voltage B: Short term fuel trim
1A	26	2	Oxygen Sensor 7 A: Voltage B: Short term fuel trim
1B	27	2	Oxygen Sensor 8 A: Voltage B: Short term fuel trim
1C	28	1	OBD standards this vehicle conforms to	1	250		enumerated. See below
1D	29	1	Oxygen sensors present (in 4 banks)				Similar to PID $13, but [A0..A7] == [B1S1, B1S2, B2S1, B2S2, B3S1, B3S2, B4S1, B4S2]
1E	30	1	Auxiliary input status				A0 == Power Take Off (PTO) status (1 == active) [A1..A7] not used
1F	31	2	Run time since engine start	0	65,535	s	${\displaystyle 256A+B}$
20	32	4	PIDs supported [$21 - $40]				Bit encoded [A7..D0] == [PID $21..PID $40] See below
21	33	2	Distance traveled with malfunction indicator lamp (MIL) on	0	65,535	km	${\displaystyle 256A+B}$
22	34	2	Fuel Rail Pressure (relative to manifold vacuum)	0	5177.265	kPa	${\displaystyle 0.079(256A+B)}$
23	35	2	Fuel Rail Gauge Pressure (diesel, or gasoline direct injection)	0	655,350	kPa	${\displaystyle 10(256A+B)}$
24	36	4	Oxygen Sensor 1 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Voltage	0 0	< 2 < 8	ratio V	$${\displaystyle {\frac {2}{65536}}(256A+B)}$$$${\displaystyle {\frac {8}{65536}}(256C+D)}$$
25	37	4	Oxygen Sensor 2 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Voltage
26	38	4	Oxygen Sensor 3 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Voltage
27	39	4	Oxygen Sensor 4 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Voltage
28	40	4	Oxygen Sensor 5 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Voltage
29	41	4	Oxygen Sensor 6 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Voltage
2A	42	4	Oxygen Sensor 7 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Voltage
2B	43	4	Oxygen Sensor 8 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Voltage
2C	44	1	Commanded EGR	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$
2D	45	1	EGR Error	-100	99.2	%	${\displaystyle {\tfrac {100}{128}}A-100}$
2E	46	1	Commanded evaporative purge	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$
2F	47	1	Fuel Tank Level Input	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$
30	48	1	Warm-ups since codes cleared	0	255		${\displaystyle A}$
31	49	2	Distance traveled since codes cleared	0	65,535	km	${\displaystyle 256A+B}$
32	50	2	Evap. System Vapor Pressure	-8,192	8191.75	Pa	${\displaystyle {\frac {256A+B}{4}}}$(AB is two's complement signed)[3]
33	51	1	Absolute Barometric Pressure	0	255	kPa	${\displaystyle A}$
34	52	4	Oxygen Sensor 1 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Current	0 -128	< 2 <128	ratio mA	$${\displaystyle {\frac {2}{65536}}(256A+B)}$$$${\displaystyle {\frac {256C+D}{256}}-128}$$
35	53	4	Oxygen Sensor 2 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Current
36	54	4	Oxygen Sensor 3 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Current
37	55	4	Oxygen Sensor 4 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Current
38	56	4	Oxygen Sensor 5 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Current
39	57	4	Oxygen Sensor 6 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Current
3A	58	4	Oxygen Sensor 7 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Current
3B	59	4	Oxygen Sensor 8 AB: Air-Fuel Equivalence Ratio (lambda,λ) CD: Current
3C	60	2	Catalyst Temperature: Bank 1, Sensor 1	-40	6,513.5	°C	${\displaystyle {\frac {256A+B}{10}}-40}$
3D	61	2	Catalyst Temperature: Bank 2, Sensor 1
3E	62	2	Catalyst Temperature: Bank 1, Sensor 2
3F	63	2	Catalyst Temperature: Bank 2, Sensor 2
40	64	4	PIDs supported [$41 - $60]				Bit encoded [A7..D0] == [PID $41..PID $60] See below
41	65	4	Monitor status this drive cycle				Bit encoded. See below
42	66	2	Control module voltage	0	65.535	V	${\displaystyle {\frac {256A+B}{1000}}}$
43	67	2	Absolute load value	0	25,700	%	${\displaystyle {\tfrac {100}{255}}(256A+B)}$
44	68	2	Commanded Air-Fuel Equivalence Ratio (lambda,λ)	0	< 2	ratio	${\displaystyle {\tfrac {2}{65536}}(256A+B)}$
45	69	1	Relative throttle position	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$
46	70	1	Ambient air temperature	-40	215	°C	${\displaystyle A-40}$
47	71	1	Absolute throttle position B	0	100	%	${\displaystyle {\frac {100}{255}}A}$
48	72	1	Absolute throttle position C
49	73	1	Accelerator pedal position D
4A	74	1	Accelerator pedal position E
4B	75	1	Accelerator pedal position F
4C	76	1	Commanded throttle actuator
4D	77	2	Time run with MIL on	0	65,535	min	${\displaystyle 256A+B}$
4E	78	2	Time since trouble codes cleared
4F	79	4	Maximum value for Fuel–Air equivalence ratio, oxygen sensor voltage, oxygen sensor current, and intake manifold absolute pressure	0, 0, 0, 0	255, 255, 255, 2550	ratio, V, mA, kPa	${\displaystyle A}$, ${\displaystyle B}$, ${\displaystyle C}$, ${\displaystyle D\times 10}$
50	80	4	Maximum value for air flow rate from mass air flow sensor	0	2550	g/s	${\displaystyle A\times 10}$; ${\displaystyle B}$, ${\displaystyle C}$, and ${\displaystyle D}$ are reserved for future use
51	81	1	Fuel Type				From fuel type table see below
52	82	1	Ethanol fuel %	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$
53	83	2	Absolute Evap system Vapor Pressure	0	327.675	kPa	${\displaystyle {\frac {256A+B}{200}}}$
54	84	2	Evap system vapor pressure	-32,768	32,767	Pa	${\displaystyle 256A+B}$(AB is two's complement signed)[3]
55	85	2	Short term secondary oxygen sensor trim, A: bank 1, B: bank 3	-100	99.2	%	${\displaystyle {\frac {100}{128}}A-100}$${\displaystyle {\frac {100}{128}}B-100}$
56	86	2	Long term secondary oxygen sensor trim, A: bank 1, B: bank 3
57	87	2	Short term secondary oxygen sensor trim, A: bank 2, B: bank 4
58	88	2	Long term secondary oxygen sensor trim, A: bank 2, B: bank 4
59	89	2	Fuel rail absolute pressure	0	655,350	kPa	${\displaystyle 10(256A+B)}$
5A	90	1	Relative accelerator pedal position	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$
5B	91	1	Hybrid battery pack remaining life	0	100	%	${\displaystyle {\tfrac {100}{255}}A}$
5C	92	1	Engine oil temperature	-40	210	°C	${\displaystyle A-40}$
5D	93	2	Fuel injection timing	-210.00	301.992	°	${\displaystyle {\frac {256A+B}{128}}-210}$
5E	94	2	Engine fuel rate	0	3212.75	L/h	${\displaystyle {\frac {256A+B}{20}}}$
5F	95	1	Emission requirements to which vehicle is designed				Bit Encoded
60	96	4	PIDs supported [$61 - $80]				Bit encoded [A7..D0] == [PID $61..PID $80] See below
61	97	1	Driver's demand engine - percent torque	-125	130	%	${\displaystyle A-125}$
62	98	1	Actual engine - percent torque	-125	130	%	${\displaystyle A-125}$
63	99	2	Engine reference torque	0	65,535	N⋅m	${\displaystyle 256A+B}$
64	100	5	Engine percent torque data	-125	130	%	${\displaystyle A-125}$ Idle ${\displaystyle B-125}$ Engine point 1${\displaystyle C-125}$ Engine point 2 ${\displaystyle D-125}$ Engine point 3${\displaystyle E-125}$ Engine point 4
65	101	2	Auxiliary input / output supported				Bit Encoded
66	102	5	Mass air flow sensor	0	2047.96875	g/s	[A0]== Sensor A Supported [A1]== Sensor B Supported Sensor A:${\displaystyle {\frac {256B+C}{32}}}$Sensor B:${\displaystyle {\frac {256D+E}{32}}}$
67	103	3	Engine coolant temperature	-40	215	°C	[A0]== Sensor 1 Supported [A1]== Sensor 2 Supported Sensor 1:${\displaystyle B-40}$Sensor 2:${\displaystyle C-40}$
68	104	3	Intake air temperature sensor	-40	215	°C	[A0]== Sensor 1 Supported [A1]== Sensor 2 Supported Sensor 1:${\displaystyle B-40}$Sensor 2:${\displaystyle C-40}$
69	105	7	Actual EGR, Commanded EGR, and EGR Error
6A	106	5	Commanded Diesel intake air flow control and relative intake air flow position
6B	107	5	Exhaust gas recirculation temperature
6C	108	5	Commanded throttle actuator control and relative throttle position
6D	109	11	Fuel pressure control system
6E	110	9	Injection pressure control system
6F	111	3	Turbocharger compressor inlet pressure
70	112	10	Boost pressure control
71	113	6	Variable Geometry turbo (VGT) control
72	114	5	Wastegate control
73	115	5	Exhaust pressure
74	116	5	Turbocharger RPM
75	117	7	Turbocharger temperature
76	118	7	Turbocharger temperature
77	119	5	Charge air cooler temperature (CACT)
78	120	9	Exhaust Gas temperature (EGT) Bank 1				Special PID. See below
79	121	9	Exhaust Gas temperature (EGT) Bank 2				Special PID. See below
7A	122	7	Diesel particulate filter (DPF) differential pressure
7B	123	7	Diesel particulate filter (DPF)
7C	124	9	Diesel Particulate filter (DPF) temperature			°C	${\displaystyle {\frac {256A+B}{10}}-40}$
7D	125	1	NOx NTE (Not-To-Exceed) control area status
7E	126	1	PM NTE (Not-To-Exceed) control area status
7F	127	13	Engine run time [b]			s
80	128	4	PIDs supported [$81 - $A0]				Bit encoded [A7..D0] == [PID $81..PID $A0] See below
81	129	41	Engine run time for Auxiliary Emissions Control Device(AECD)
82	130	41	Engine run time for Auxiliary Emissions Control Device(AECD)
83	131	9	NOx sensor
84	132	1	Manifold surface temperature
85	133	10	NOx reagent system			%	${\displaystyle {\tfrac {100}{255}}E}$
86	134	5	Particulate matter (PM) sensor
87	135	5	Intake manifold absolute pressure
88	136	13	SCR Induce System
89	137	41	Run Time for AECD #11-#15
8A	138	41	Run Time for AECD #16-#20
8B	139	7	Diesel Aftertreatment
8C	140	17	O2 Sensor (Wide Range)
8D	141	1	Throttle Position G	0	100	%
8E	142	1	Engine Friction - Percent Torque	-125	130	%	${\displaystyle A-125}$
8F	143	7	PM Sensor Bank 1 & 2
90	144	3	WWH-OBD Vehicle OBD System Information			h
91	145	5	WWH-OBD Vehicle OBD System Information			h
92	146	2	Fuel System Control
93	147	3	WWH-OBD Vehicle OBD Counters support			h
94	148	12	NOx Warning And Inducement System
98	152	9	Exhaust Gas Temperature Sensor
99	153	9	Exhaust Gas Temperature Sensor
9A	154	6	Hybrid/EV Vehicle System Data, Battery, Voltage
9B	155	4	Diesel Exhaust Fluid Sensor Data			%	${\displaystyle {\tfrac {100}{255}}D}$
9C	156	17	O2 Sensor Data
9D	157	4	Engine Fuel Rate			g/s
9E	158	2	Engine Exhaust Flow Rate			kg/h
9F	159	9	Fuel System Percentage Use
A0	160	4	PIDs supported [$A1 - $C0]				Bit encoded [A7..D0] == [PID $A1..PID $C0] See below
A1	161	9	NOx Sensor Corrected Data			ppm
A2	162	2	Cylinder Fuel Rate	0	2047.96875	mg/stroke	${\displaystyle {\frac {256A+B}{32}}}$
A3	163	9	Evap System Vapor Pressure			Pa
A4	164	4	Transmission Actual Gear	0	65.535	ratio	[A1]==Supported ${\displaystyle {\frac {256C+D}{1000}}}$
A5	165	4	Commanded Diesel Exhaust Fluid Dosing	0	127.5	%	[A0]= 1:Supported; 0:Unsupported ${\displaystyle {\frac {B}{2}}}$
A6	166	4	Odometer [c]	0	429 496 729,5	km	${\displaystyle {\frac {A(2^{24})+B(2^{16})+C(2^{8})+D}{10}}}$
A7	167	4	NOx Sensor Concentration Sensors 3 and 4
A8	168	4	NOx Sensor Corrected Concentration Sensors 3 and 4
A9	169	4	ABS Disable Switch State				[A0]= 1:Supported; 0:Unsupported [B0]= 1:Yes;0:No
C0	192	4	PIDs supported [$C1 - $E0]				Bit encoded [A7..D0] == [PID $C1..PID $E0] See below
C3	195	2	Fuel Level Input A/B	0	25,700	%	Returns numerous data, including Drive Condition ID and Engine Speed*
C4	196	8	Exhaust Particulate Control System Diagnostic Time/Count	0	4,294,967,295	seconds / Count	B5 is Engine Idle Request B6 is Engine Stop Request* First byte = Time in seconds Second byte = Count
C5	197	4	Fuel Pressure A and B	0	5,177	kPa
C6	198	7	Byte 1 - Particulate control - driver inducement system status Byte 2,3 - Removal or block of the particulate aftertreatment system counter Byte 4,5 - Liquid regent injection system (e.g. fuel-borne catalyst) failure counter Byte 6,7 - Malfunction of Particulate control monitoring system counter	0	65,535	h
C7	199	2	Distance Since Reflash or Module Replacement	0	65,535	km
C8	200	1	NOx Control Diagnostic (NCD) and Particulate Control Diagnostic (PCD) Warning Lamp status	-	-	Bit
PID (hex)	PID (Dec)	Dado returnado	Descrição	Min valor	Max valor	Unit	Formula[a]

Notas

1. In the formula column, letters A, B, C, etc. represent the first, second, third, etc. byte of the data. For example, for two data bytes 0F 19, A = 0F and B = 19. Where a (?) appears, contradictory or incomplete information was available.
2. Starting with MY 2010 the California Air Resources Board mandated that all diesel vehicles must supply total engine hours^[4]
3. Starting with MY 2019 the California Air Resources Board mandated that all vehicles must supply odometer^[4]