The PR4 ECU was produced in two distinct hardware generations to support different OBD standards. Identification of the specific variant is required for tuning, diagnostics, and hardware modification.

Hardware Variants#

The PR4 platform is divided into the following generations:

• OBD0 PR4: Found in early 1990–1991 Integra models.
• OBD1 PR4: Found in 1992–1993 Integra models.

Important

OBD0 and OBD1 PR4 units are not directly interchangeable due to differences in connector pinouts, internal processor architecture, and communication protocols.

Technical Specifications#

Related Documentation#

For detailed pinouts, component traces, and modification guides, refer to the specific documentation for each generation:

• PR4 OBD0 Reference0
• PR4 OBD1 Reference0