Navigating the intricacies of OBD2 compliance in Nissan 240sx models, particularly those from the 1995 model year, can be confusing. A common question among enthusiasts and mechanics revolves around identifying whether a 240sx is truly OBD2 compliant. This often hinges on understanding the Engine Control Unit (ECU) and its corresponding codes.
The transition to OBD2 for the 240sx wasn’t a straightforward year-by-year switch. While 1996 models are definitively OBD2, the 1995 model year presents a unique case. Depending on the manufacturing date, a 1995 240sx might have an OBD1 or OBD2 compliant ECU. This distinction is crucial for diagnostics, modifications, and ensuring emissions compliance.
To clarify this, examining the ECU code is essential. Here’s a breakdown of 240sx ECU codes, categorized by model year and OBD compliance:
| ECU Code | Model Year | Transmission | Emissions | OBD Compliance | Notes |
|---|---|---|---|---|---|
| 10 | 89-90 | MT | Federal | OBDI | KA24E Engine |
| 11 | 89-90 | AT | Federal | OBDI | KA24E Engine |
| 14 | 89-90 | MT | California | OBDI | KA24E Engine |
| 15 | 89-90 | AT | California | OBDI | KA24E Engine |
| 24 | 91-94 | MT | ? | OBDI | KA24DE Engine |
| 25 | 91-94 | AT | ? | OBDI | KA24DE Engine |
| 28 | 91-94 | MT | Federal | OBDI | KA24DE Engine |
| 29 | 91-94 | AT | California | OBDI | KA24DE Engine |
| 30 | 91-94 | MT | California | OBDI | KA24DE Engine |
| PW | 91-94 | ? | ? | OBDI | KA24DE Engine |
| HT | 95 (pre-10/94) | MT | OBDI Emissions | OBDI | (A18-E07-G90) Manufactured before Oct 1994 |
| HU | 95 (pre-10/94) | AT | OBDI Emissions | OBDI | (A18-E07-G91) Manufactured before Oct 1994 |
| 3C | 95 (post-9/94) | MT | OBDII Emissions | OBDII | (A18-892-G00) Manufactured after Sep 1994 |
| 3D | 95 (post-9/94) | AT | OBDII Emissions | OBDII | (?) Manufactured after Sep 1994 |
| CA | 96 | MT | OBDII Emissions | OBDII | (A18-E27-G46) SE Model |
| CB | 96 | AT | OBDII Emissions | OBDII | (?) |
| NF | 97-98 | AT | OBDII Emissions | OBDII | (?) |
| J7 | 97-98 | AT | OBDII Emissions | OBDII | (A18-H64-GA4) SE Model |
| WM | 97-98 | MT | OBDII Emissions | OBDII | (A18-F34-G16) |
For 1995 240sx models, ECUs marked with ‘HT’ or ‘HU’ are OBDI compliant and typically found in cars manufactured before October 1994. Conversely, ECUs with codes ‘3C’ and ‘3D’ generally indicate OBD2 compliance and are found in later 1995 productions (post-September 1994). All 1996-1998 240sx models are consistently OBD2 compliant.
Therefore, when determining 240sx Obd2 compliance, especially for a 1995 model, physically checking the ECU code is the most reliable method. This table serves as a valuable guide for identifying the OBD standard of your 240sx, ensuring accurate diagnostics and modifications.
