OBD2 PID Overview: Lookup, Converter, Table, CSV and DBC

ByMAE Learning
Automotive Diagnostics

OBD2 PID Overview: Lookup, Converter, Table, CSV and DBC Tools

OBD2 Parameter IDs, or PIDs, provide standardized ways to request diagnostic data from an emissions-related vehicle ECU. For an engineer, the challenge is not only knowing the PID number. You also need to know the service, request format, response bytes, scaling formula, units, supported vehicles, and the difference between a standardized OBD2 PID and an OEM-specific CAN signal.

OBD2 PID Mode 01 CAN Diagnostics Lookup Tool CSV DBC
01

What Is an OBD2 PID?

An OBD2 PID is a Parameter ID used within an OBD2 diagnostic service to identify a particular piece of vehicle data. A diagnostic tester sends a request containing a service mode and PID. The ECU responds with data bytes. The tester then converts those bytes into an engineering value.

Diagnostic Tester Scan Tool / Application Vehicle Network CAN / Other OBD Transport ECU Diagnostic Server OBD2 PID Data Path Request → Service / PID → ECU Processing → Response Bytes Response Bytes → Formula → Physical Value → Display
02

Why OBD2 PIDs Matter

Live Vehicle Data

PIDs provide diagnostic access to parameters such as engine speed, coolant temperature, vehicle speed and calculated engine load.

Standardized Diagnostics

Standardized PIDs provide a common diagnostic interface for supported emissions-related data across compliant vehicles.

Engineering Analysis

PID decoding helps engineers validate diagnostic communication and compare raw ECU response bytes with expected physical values.

03

OBD2 Mode 01 and PID Requests

Mode 01 is used to request current powertrain data. A typical request contains the service mode followed by the requested PID.

Typical Mode 01 Request 01 XX

Here, 01 represents the current-data service and XX represents the PID.

Positive Response 41 XX A B C D …
Important: The response format depends on the PID. The bytes after the response service and PID are interpreted according to the definition of the requested parameter.
04

OBD2 PID Lookup and Converter Tool

Use the lookup tool below to inspect common standardized Mode 01 PIDs. Enter a PID in hexadecimal, decimal, or search by name. The converter shows the expected response structure, formula and physical unit.

Common standardized PIDs loaded
PID Parameter Response Bytes Formula Unit
0x00 PIDs supported [01-20] A, B, C, D Bit map Bit field
0x01 Monitor status since DTCs cleared A, B, C, D Bit fields Flags
0x04 Calculated engine load A A × 100 / 255 %
0x05 Engine coolant temperature A A − 40 °C
0x06 Short-term fuel trim Bank 1 A (A − 128) × 100 / 128 %
0x07 Long-term fuel trim Bank 1 A (A − 128) × 100 / 128 %
0x0B Intake manifold absolute pressure A A kPa
0x0C Engine speed A, B ((A × 256) + B) / 4 rpm
0x0D Vehicle speed A A km/h
0x0F Intake air temperature A A − 40 °C
0x10 MAF air flow rate A, B ((A × 256) + B) / 100 g/s
0x11 Throttle position A A × 100 / 255 %
0x1F Run time since engine start A, B (A × 256) + B s
0x21 Distance traveled with MIL on A, B (A × 256) + B km
0x2F Fuel tank level input A A × 100 / 255 %
0x31 Distance traveled since DTCs cleared A, B (A × 256) + B km
0x33 Barometric pressure A A kPa
0x42 Control module voltage A, B ((A × 256) + B) / 1000 V
0x46 Ambient air temperature A A − 40 °C
0x5C Engine oil temperature A A − 40 °C
0x5E Engine fuel rate A, B ((A × 256) + B) / 20 L/h
Compatibility matters: A vehicle does not necessarily support every standardized PID. First query the supported-PID bitmap, then request a PID supported by the ECU and vehicle configuration.
05

How the PID Converter Works

Request 01 0C ECU Response 41 0C A B Raw Data A = 0x1A, B = 0xF0 Formula Conversion ((A × 256) + B) / 4 Physical Value Engine Speed = 1756 rpm Example raw response converted according to PID 0x0C
06

Worked PID Conversion Example: Engine Speed

PID 0x0C represents engine speed. The response uses two data bytes, A and B. The standard conversion formula is:

Engine Speed RPM = ((A × 256) + B) / 4

Suppose the ECU responds with:

41 0C 1A F0

The response service is 0x41, the PID is 0x0C, and the data bytes are A = 0x1A and B = 0xF0.

Calculation ((26 × 256) + 240) / 4 = 1756 rpm
Engineering pattern: Request → identify PID → extract response bytes → apply PID formula → convert to physical units.
07

Interactive PID Converter

Select a common PID and enter hexadecimal response bytes. The tool applies the corresponding conversion formula.

Select a PID and enter response bytes.
08

OBD2 PID Reference Table

The following table covers commonly used standardized PIDs. The exact supported set depends on the vehicle and applicable OBD requirements.

PID Parameter Bytes Conversion Unit Typical Engineering Use
0x04 Calculated engine load 1 A × 100 / 255 % Engine operating load
0x05 Engine coolant temperature 1 A − 40 °C Thermal monitoring
0x06 Short-term fuel trim Bank 1 1 (A − 128) × 100 / 128 % Fuel control analysis
0x0B Intake manifold absolute pressure 1 A kPa Engine load analysis
0x0C Engine speed 2 ((A × 256) + B) / 4 rpm Engine speed validation
0x0D Vehicle speed 1 A km/h Vehicle speed
0x0F Intake air temperature 1 A − 40 °C Air temperature
0x10 MAF air flow rate 2 ((A × 256) + B) / 100 g/s Air mass measurement
0x11 Throttle position 1 A × 100 / 255 % Throttle monitoring
0x1F Run time since engine start 2 (A × 256) + B s Engine operating duration
0x2F Fuel tank level input 1 A × 100 / 255 % Fuel level
0x31 Distance since DTCs cleared 2 (A × 256) + B km Diagnostic history
0x33 Barometric pressure 1 A kPa Pressure reference
0x42 Control module voltage 2 ((A × 256) + B) / 1000 V ECU supply monitoring
0x46 Ambient air temperature 1 A − 40 °C Ambient condition
0x5C Engine oil temperature 1 A − 40 °C Oil thermal monitoring
0x5E Engine fuel rate 2 ((A × 256) + B) / 20 L/h Fuel consumption analysis
09

OBD2 PID to CAN Data Flow

On a CAN-based diagnostic connection, the diagnostic application does not normally read an OBD2 PID as though the PID were a native CAN signal. The diagnostic request and response use diagnostic communication rules. The underlying ECU application data might originate from internal software variables or signals.

Scan Tool OBD2 PID request CAN Interface CAN diagnostic transport Gateway / ECU Diagnostic routing Powertrain ECU PID service implementation Example Request 01 0C Request current engine speed 41 0C A B
10

OBD2 PID vs DBC Signal

An OBD2 PID and a DBC signal both involve interpreting bytes, but they belong to different layers and use different definitions.

Feature OBD2 PID DBC Signal
Purpose Diagnostic parameter access Vehicle network signal description
Identifier PID within a diagnostic service CAN message ID plus signal definition
Payload definition Defined by the PID specification Defined by the DBC database
Scaling PID-specific formula Signal factor and offset
Typical access Diagnostic request and response Periodic/event CAN message reception
Example Mode 01 PID 0x0C EngineSpeed signal in a CAN message
Ownership Standardized diagnostic interface Vehicle/OEM network database
Do not assume equivalence: A PID named “Engine Speed” and a DBC signal named “EngineSpeed” might represent the same physical quantity while using different CAN IDs, byte positions, scaling, update rates and diagnostic paths.
11

OBD2 Data to DBC Conversion Concept

A DBC database describes CAN messages and signals. It does not replace the OBD2 PID definition. If you are building a gateway, logger or diagnostic application, keep the diagnostic mapping separate from the native CAN signal database.

// Diagnostic layer
OBD2 PID = 0x0C
Formula = ((A * 256) + B) / 4
Unit = “rpm”

// Native CAN layer
CAN Message ID = 0x280
Signal = “EngineSpeed”
Start Bit = 16
Length = 16
Factor = 0.25
Offset = 0
Unit = “rpm”
Key point: The example DBC values above are illustrative only. A real vehicle DBC must use the actual OEM or project-specific message and signal definition.
12

CSV Format for an OBD2 PID Database

CSV is useful when building a lightweight PID lookup database, test automation input, spreadsheet reference or software import file.

PID,Parameter,Bytes,Formula,Unit,Service 04,Calculated Engine Load,1,A*100/255,%,01 05,Engine Coolant Temperature,1,A-40,degC,01 0C,Engine Speed,2,((A*256)+B)/4,rpm,01 0D,Vehicle Speed,1,A,km/h,01 0F,Intake Air Temperature,1,A-40,degC,01 10,MAF Air Flow,2,((A*256)+B)/100,g/s,01 11,Throttle Position,1,A*100/255,%,01 1F,Run Time Since Engine Start,2,(A*256)+B,s,01 2F,Fuel Tank Level,1,A*100/255,%,01 42,Control Module Voltage,2,((A*256)+B)/1000,V,01 46,Ambient Air Temperature,1,A-40,degC,01 5C,Engine Oil Temperature,1,A-40,degC,01 5E,Engine Fuel Rate,2,((A*256)+B)/20,L/h,01
The CSV contains the common PID reference data shown above.
13

DBC-Oriented Engineering View

When engineers work with vehicle CAN databases, they often need to map diagnostic concepts to native CAN signals. A DBC-style signal definition normally includes a CAN message identifier, signal start bit, signal length, byte order, signedness, factor, offset and physical limits.

DBC Field Meaning Example
Message ID CAN identifier carrying the signal 0x280
Signal Name Logical signal name EngineSpeed
Start Bit Location of the signal in the CAN payload 16
Length Number of signal bits 16
Byte Order Intel or Motorola representation Project-specific
Factor Raw-to-physical scaling 0.25
Offset Physical-value offset 0
Unit Engineering unit rpm
Typical DBC Signal Conversion Physical Value = Raw Value × Factor + Offset
14

OBD2 Diagnostic Sequence

1

Tester Identifies the Required PID

The diagnostic application selects the service and PID, such as Mode 01 PID 0x0C for engine speed.

2

Tester Sends the Request

The request is transported through the vehicle diagnostic interface. For CAN-based OBD communication, the request is carried through CAN diagnostic addressing and transport rules.

3

ECU Processes the PID

The diagnostic software identifies the requested PID and obtains the corresponding current data from the ECU application.

4

ECU Builds the Response

The ECU encodes the physical value into the PID-defined response bytes.

5

Tester Decodes the Bytes

The diagnostic application applies the PID conversion formula and displays the physical value.

15

Common OBD2 PID Debugging Problems

PID Not Supported

The ECU or vehicle does not support the requested PID. Check the supported-PID bitmap before treating the request as a fault.

Wrong Formula

A raw response is decoded with the wrong scaling rule, producing an incorrect physical value.

Wrong Byte Order

Multi-byte parameters require the correct byte order. Swapping A and B produces a different raw value.

Stale Data

A correct response does not guarantee a fresh application value. Check ECU data acquisition and update timing when validating live data.

Confusing PID With CAN ID

A PID identifies a diagnostic parameter. A CAN identifier identifies a CAN frame used by the communication system.

Mixing OBD2 and OEM Data

OEM-specific diagnostic services and proprietary CAN signals often use different definitions from standardized OBD2 PIDs.

16

Recommended PID Debugging Workflow

Tester Side

  • Confirm physical connection.
  • Confirm diagnostic addressing.
  • Confirm service and PID.
  • Check supported-PID response.
  • Capture the complete response.
  • Decode bytes independently.

ECU Side

  • Verify diagnostic service configuration.
  • Verify PID implementation.
  • Check source application signal.
  • Check scaling and encoding.
  • Check response timing.
  • Compare with internal ECU data.
Useful validation technique: Record the raw diagnostic request and response alongside the physical measurement. This makes scaling and encoding errors easier to identify.
17

OBD2 PID, UDS and DBC: Do Not Mix the Layers

Concept Primary Role Example
OBD2 PID Standardized vehicle diagnostic parameter Mode 01 PID 0x0C
UDS Service General diagnostic application protocol 0x22 ReadDataByIdentifier
CAN Identifier Identifies a CAN frame for communication/arbitration 0x7E8
CAN Signal Application data encoded inside a CAN frame EngineSpeed
DBC Database description of CAN messages and signals Message and signal definitions
Layering matters: An OBD2 PID is a diagnostic parameter identifier. A UDS Data Identifier has a different role. A CAN ID identifies a CAN frame. A DBC signal describes data inside a CAN message.
18

Interview Questions

1. What is an OBD2 PID?

A Parameter ID identifies a diagnostic parameter within an OBD2 service.

2. What does Mode 01 represent?

Mode 01 requests current powertrain-related diagnostic data.

3. What is the positive response for Mode 01?

The positive response service is Mode 01 plus 0x40, giving 0x41.

4. How is PID 0x0C converted?

Engine speed uses two data bytes: ((A × 256) + B) / 4, producing rpm.

5. What does PID 0x0D represent?

PID 0x0D represents vehicle speed. The response byte is interpreted directly as km/h.

6. What is the difference between an OBD2 PID and a CAN ID?

The PID identifies a diagnostic parameter. The CAN ID identifies a CAN frame used by the communication network.

7. What is a DBC?

A DBC is a CAN database format used to describe messages and signals, including positions, lengths, byte order, scaling and units.

8. Does every ECU support every OBD2 PID?

No. Supported PIDs depend on the vehicle, ECU configuration and applicable OBD requirements.

9. Why should raw response bytes be logged?

Raw bytes allow engineers to independently verify the conversion formula, byte order and response structure.

10. Is an OBD2 PID equivalent to a UDS DID?

No. They are different diagnostic concepts with different definitions and protocol contexts.

19

Key Takeaways

01. A PID identifies a diagnostic parameter. The service and PID together determine the requested data.
02. Raw bytes need conversion. The physical value comes from the PID-specific formula.
03. PID support varies. Check supported-PID information before requesting live data.
04. PID and CAN ID are different. Do not treat a diagnostic PID as a CAN frame identifier.
05. DBC and OBD2 serve different purposes. A DBC describes CAN messages and signals. OBD2 defines diagnostic access.
06. Keep raw and physical values together. This makes diagnostic validation and debugging easier.
07. Use CSV for tooling. A structured CSV provides a convenient reference database for scripts, test automation and engineering tools.
08. Validate against the vehicle. A standardized PID definition does not guarantee support or identical application behavior across every vehicle.
20

FAQ

An OBD2 PID is a Parameter ID used to identify a diagnostic data item within an OBD2 service.
Mode 01 is used to request current powertrain-related data.
PID 0x0C represents engine speed. The response uses two bytes and the standard conversion is ((A × 256) + B) / 4 rpm.
PID 0x0D represents vehicle speed. The response byte is interpreted as km/h.
An OBD2 PID belongs to diagnostic communication. A DBC signal describes application data inside a CAN message.
No direct universal conversion exists. A DBC requires the actual CAN message ID, signal location, length, byte order, scaling and other network-specific information.
Possible causes include unsupported PID, incorrect diagnostic addressing, communication problems, ECU state, request formatting or vehicle-specific diagnostic restrictions.
A lookup table keeps PID numbers, formulas, byte counts and units consistent across diagnostic software, test scripts and engineering documentation.

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