Engine swaps are a popular modification for Honda Civic enthusiasts looking to boost performance. Navigating the wiring, especially when dealing with VTEC (Variable Valve Timing and Lift Electronic Control) and different OBD (On-Board Diagnostics) systems, can be challenging. This guide provides a comprehensive overview of Obd2 Vtec Wiring for 1992-2000 Honda Civics, ensuring a smoother engine swap process. Whether you’re upgrading to a VTEC engine or dealing with different OBD generations, understanding the wiring is crucial for a successful swap.
Swapping an OBD1 Engine/ECU into an OBD1 Civic
For those keeping it simple with an OBD1 engine and ECU in an OBD1 Civic, the process is generally straightforward.
(Note: For all 1992 Civics, the VTEC wiring is pre-run on the shock tower to ECU harness. Utilizing a 1992-1995 EX/Si engine harness makes VTEC installation plug and play.)
*D16Z6/D15B (JDM)/Mini Me using P28 ECU**
If your JDM D15B engine lacks a VTEC pressure switch, you’ll need to install one. Simply remove the existing bolt and replace it with a VTEC pressure switch from any 1990-2001 Civic, Integra, or Accord.
For DX/LX – D15B7 models, VTEC solenoid and VTEC pressure switch wiring to the P28 ECU is necessary. All other connections are plug and play.
For CX – D15B8 models, similar to DX/LX, you’ll need to wire the VTEC solenoid and pressure switch to the P28 ECU. Additionally, if your CX model is not a 4-wire O2 sensor configuration, wiring the three additional O2 sensor connections to the ECU is required.
For VX – D15Z1 models, VTEC wiring follows the same procedure as above. For knock sensor and IAB (Intake Air Bypass) wiring, refer to Figure 1. (Note: If using a chipped P28 ECU, IAB and knock sensor wiring are typically not needed). If your VX model has a 7-wire O2 sensor, conversion to a 4-wire setup is necessary.
B16A3/B17A/B18C1/B18C (OBD1 JDM) using chipped P28/P30/P61/P72 ECU
For EX/Si – D16Z6 models, VTEC wiring is plug and play. Knock sensor and IAB wiring may be required (Figure 1), but are often bypassed with a chipped P28 ECU. All other wiring is plug and play.
For DX/LX – D15B7 models, VTEC wiring is needed as shown in Figure 1. Knock sensor and IAB wiring (Figure 1) are also needed, but can be skipped with a chipped P28 ECU. All other wiring is plug and play.
For CX – D15B8 models, VTEC wiring and knock/IAB wiring (Figure 1) are required, with the option to bypass knock/IAB with a chipped P28. For non 4-wire O2 sensor CX models, wire the additional O2 connections as in Figure 1. All other wiring is plug and play.
For VX – D15Z1 models, reuse the existing VTEC solenoid and pressure switch wiring for a plug and play VTEC setup. If your VX has a 7-wire O2 sensor, convert it to a 4-wire configuration.
B18A (OBD1)/B18B in DX/CX/VX/EX using P74/P75 ECU/all chipped OBD1 ECU’s
For LX/DX/EX – D15B7/D16Z6 models, this swap is plug and play.
For CX/VX – D15B8/D15Z1 models, it’s also plug and play. For 1-wire O2 sensor CX models, wiring in the additional 3 wires for a 4-wire O2 sensor (Figure 1) is necessary. VX models with 7-wire O2 sensors need to be converted to 4-wire.
OBD2 Engine/OBD1 ECU into OBD1 Vehicle
(Note: Again, for 1992 Civics, VTEC is pre-wired on the shock tower to ECU harness, making VTEC plug and play with a 92-95 EX/SI engine harness.)
D16Y8 using P28 ECU
For EX/Si/VX – D16Z6/D15Z1 models, this swap is mostly plug and play, including VTEC. The knock sensor will not be utilized with the P28 ECU. The EX/Si/VX distributor may not directly bolt onto the Y8 head. While usable, not all mounting points will align. To use the Y8 distributor, an OBD2A or OBD2B to OBD1 adapter harness is required. The intake air temperature sensor (IAT) is not located on the Y8 intake manifold. Relocate your IAT sensor to the intake arm (Figure 3) or use a Z6/Z1 manifold. Reuse Z6 injectors as Y8 injectors will not plug in correctly. For VX models, use EX/SI/DX injectors for similar flow rates. Also, reuse the Z6/Z1 alternator due to different plug styles on the Y8 alternator. The CKF (Crankshaft Fluctuation Sensor) on the Y8 will not be used; secure it out of the way. For VX models, convert the 5-wire O2 sensor to a 4-wire sensor.
For LX/DX/CX – D15B7/D15B8 models, the swap is mostly plug and play. VTEC solenoid and pressure switch wiring (Figure 1) is necessary. Reuse the DX/CX distributor as it will bolt up directly. To use the Y8 distributor, an OBD2A or OBD2B to OBD1 adapter harness will be needed. Relocate the IAT sensor to the intake arm (Figure 3) or use a CX/DX manifold. DX injectors can be reused as they have the same flow rate. For CX models, consider EX/SI/DX injectors for higher flow rates, similar to Y8 injectors. Reuse the CX/DX alternator as the Y8 alternator uses a different plug style. The CKF sensor on the Y8 engine will not be used.
B16A2/B18C1 (OBD2)/B18C5 using chipped P28/P30/P72
For EX/SI/VX – D16Z6/D15Z1 models, the swap is mostly plug and play, including VTEC. The knock sensor is not used with the P28 ECU, but will be with other ECUs. To use the A2/C1/C5 distributor, an OBD2A or OBD2B to OBD1 adapter harness is needed. Relocate the IAT sensor to the intake arm. Reuse Z6 injectors, and for VX models, use EX/SI/DX injectors for similar flow rates. An OBD1 B-series alternator is required for plug and play compatibility. The CKF sensor will not be used. For VX models, convert the 5-wire O2 sensor to 4-wire.
For DX/CX – D15B7/D15B8 models, the swap is mostly plug and play. VTEC wiring is needed as shown in Figure 1. The knock sensor is not used with the P28 ECU but will be with others. An OBD2A or OBD2B to OBD1 distributor adapter is needed for the A2/C1/C5 distributor. Relocate the IAT sensor to the intake arm. Reuse DX injectors, and for CX models, use EX/SI/DX injectors for appropriate flow rates. An OBD1 B-series alternator is required. The CKF sensor will not be used. For 1-wire O2 CX models, convert to a 4-wire setup using Figure 1.
B18B/B20B/Z (OBD2) using P75 ECU
For EX/SI/VX/DX/CX – D16Z6/D15Z1/D15B7/D15B8 models, the swap is mostly plug and play. For the distributor, use an OBD1 B18 distributor for plug and play or an OBD2 LS distributor with an adapter harness. An OBD1 B-series alternator is needed. For EX/SI/DX models, reuse existing injectors. For VX/CX, use EX/DX/SI injectors. The CKF sensor will not be used. For 1-wire O2 CX models, convert to 4-wire O2 using Figure 1. For VX 7-wire O2 sensors, convert to 4-wire.
OBD0 Engine into OBD1 Vehicle using OBD1 ECU
B18A (OBD0) using P75 OBD1 ECU
For EX/SI/DX/CX/VX – D16Z6/D15Z1/D15B7/D15B8 models, this swap is mostly plug and play. The alternator plugs are compatible between OBD0 and OBD1. Reuse EX/SI/DX injectors, and for CX/VX, use EX/SI/DX injectors. The fan switch location differs on OBD0 engines, being on the back of the block. Rewire the fan switch from the thermostat housing to the back of the block. Wiring order doesn’t matter. For VX 7-wire O2 sensors and CX 1-wire O2 sensors, convert to 4-wire using Figure 1.
OBD2 Engine into OBD2 Vehicle using OBD2 ECU
(NOTE: Do not mix 1996-1998 OBD2A and 1999-2000 OBD2B engine and dash harnesses when swapping engines in 96-00 Civics due to different ECU connectors.)
D16Y8 using P2P ECU
For DX/LX/CX – D16Y7 models, the swap is mostly plug and play. VTEC solenoid, VTEC pressure switch, and knock sensor wiring are required (Figure 6 for OBD2A, Figure 7 for OBD2B). The idle air control valve (IACV) needs to be wired from 3-wire to 2-wire (Figure 6 for OBD2A, Figure 7 for OBD2B). The secondary O2 sensor wiring may need lengthening with an O2 adapter if using an EX-style catalytic converter. Relocate the IAT sensor to the intake arm (Figure 8).
HX – D16Y5 models are mostly plug and play. Reuse VTEC solenoid and pressure switch. 5-speed models need knock sensor wiring (Figure 6, all 96-00 HX models are OBD2A). 7-wire O2 sensors need to be converted to 4-wire.
B16A2/B18C1/B18C5 using P30 (OBD2A)/P2T/P72
For EX – D16Y8 models, the swap is mostly plug and play. Reuse VTEC solenoid, pressure switch, and knock sensor wiring. Secondary O2 sensor may need extending. For B18C1, IABs need wiring on the P72 ECU (Figure 6 for OBD2A and Figure 7 for OBD2B). Relocate the IAT sensor to the intake arm. For B18C1 and C5, consider converting to a round-style IAT and placing the connector on the manifold (Figure 9 for plug style).
For DX/LX/CX – D16Y7 models, wiring for VTEC solenoid, pressure switch, and knock sensor is needed (Figure 6 for OBD2A, Figure 7 for OBD2B). IACV wiring from 3-wire to 2-wire is also required (Figure 6 & 7). Secondary O2 sensor wiring may need lengthening. Relocate the IAT sensor to the intake arm. For B18C1 and C5, consider the round-style IAT conversion.
For HX – D16Y5 models, reuse VTEC solenoid and pressure switch. 5-speed models need knock sensor wiring (Figure 6 – OBD2A). Convert 7-wire O2 to 4-wire.
B18B/B20B/Z using OBD2A P75 (Note: 00-01 P75 ECUs with immobilizers are not recommended.)
For EX/HX – D16Y8/D16Y5 models, this is plug and play. For HX, convert 7-wire O2 to 4-wire.
For DX/LX/CX – D16Y7 models, the swap is mostly plug and play. IACV wiring from 3-wire to 2-wire is needed (Figure 6 & 7). Secondary O2 sensor wiring may need lengthening. Relocate the IAT sensor to the intake arm.
OBD1 Engine into OBD2 Vehicle using OBD1 ECU
D16Z6 using P28 ECU
For DX/LX/CX – D16Y7 models, the swap is mostly plug and play. VTEC solenoid and pressure switch wiring are required (Figure 1). IACV wiring from 3-wire to 2-wire is also needed (Figure 6 & 7). Relocate the IAT sensor to the intake arm or rewire to OBD1 style (Figure 9). CKF, EVAP purge, and secondary O2 are eliminated. A D16Z6 distributor adapter is needed. Use Z6 injectors and remove injector “clips” for plug and play (Figure 10). Reuse the Y7 alternator or use an adapter.
For HX – D16Y5 models, VTEC is plug and play. Relocate the IAT sensor to the intake arm or rewire to OBD1 style (Figure 9). CKF, EVAP purge, EGR, and secondary O2 are eliminated. Convert 7-wire O2 to 4-wire. A D16Z6 distributor adapter is needed. Use Z6 injectors and remove clips. Reuse the Y7 alternator or use an adapter.
For EX – D16Y8 models, VTEC is plug and play. Relocate IAT sensor or rewire to OBD1 style (Figure 9). CKF, EVAP purge, EGR, and secondary O2 are eliminated. D16Z6 distributor adapter needed. Use Z6 injectors and remove clips. Reuse Y7 alternator or use an adapter.
B16A2/B18C1/B18C5 using OBD1 P30
For DX/LX/CX – D16Y7 models, the swap is mostly plug and play. VTEC solenoid, pressure switch, and knock sensor wiring are needed (Figure 1). IACV wiring from 3-wire to 2-wire is also required (Figure 6 & 7). Relocate IAT sensor or rewire to OBD1 style (Figure 9). CKF, EVAP purge, and secondary O2 are eliminated. For 96-98 Civics, use an OBD2 B-series VTEC distributor or an OBD2A to OBD1 distributor adapter. For 99-00, use an OBD2B to OBD1/2 distributor adapter and an OBD1/2 B-series DOHC VTEC distributor. Use B-series injectors and remove clips (Figure 10). Use an OBD2 B-series alternator or an OBD2-1 alternator adapter.
For HX – D16Y5 models, VTEC is plug and play. Relocate IAT sensor or rewire to OBD1 style (Figure 9). CKF, EVAP purge, EGR, and secondary O2 are eliminated. Convert 7-wire O2 to 4-wire. Use an OBD2 VTEC distributor or an OBD2A to OBD1 distributor adapter. Use B-series injectors and remove clips (Figure 10). Use an OBD2 B-series alternator or an OBD2-1 alternator adapter.
For EX – D16Y8 models, VTEC is plug and play. Knock sensor wiring is needed (Figure 1). Relocate IAT sensor or rewire to OBD1 style (Figure 9). CKF, EVAP purge, EGR, and secondary O2 are eliminated. For 96-98 Civics, use an OBD2 B-series VTEC distributor or an OBD2A to OBD1 adapter. For 99-00, use an OBD2B to OBD1/2 distributor adapter and OBD1/2 B-series DOHC VTEC distributor. Use B-series injectors and remove clips (Figure 10) or use Y8 injectors. Use an OBD2 B-series alternator or an OBD2-1 alternator adapter.
B18A/B using OBD1 P75
For DX/LX/CX – D16Y7 models, the swap is mostly plug and play. IACV wiring from 3-wire to 2-wire is needed (Figure 6 & 7). Secondary O2 sensor wiring may need lengthening. Relocate IAT sensor. CKF, EVAP purge, EGR, and secondary O2 are eliminated. Use an OBD2 B18B distributor or an OBD2A to OBD1 adapter. For 99-00 Civic, use an OBD2B to OBD1 distributor adapter with either an OBD1 or OBD2 B18A/B distributor. Use B18A/B injectors and remove clips (Figure 10). Use an OBD2 B-series alternator or an OBD2-1 alternator adapter.
For EX/HX – D16Y8/Y5 models, relocate the IAT sensor or rewire to OBD1 style (Figure 9). CKF, EVAP purge, EGR, and secondary O2 are eliminated. For 96-98 Civics, use an OBD2 B18B distributor or an OBD2A to OBD1 adapter. For 99-00, use an OBD2B to OBD1/2 distributor adapter and OBD1/2 B-series DOHC VTEC distributor. Use B18A/B injectors and remove clips (Figure 10). Use an OBD2 B-series alternator or an OBD2-1 alternator adapter. For HX, convert 7-wire O2 to 4-wire.
Disclaimer: This guide is for informational purposes only and should be used by experienced automotive technicians. Incorrect wiring can damage your vehicle. Always consult official repair manuals and wiring diagrams for your specific vehicle and engine combination. OBD2Global.com is not responsible for any damage resulting from the use of this guide.
