Listings of the trouble codes for the various engine control systems covered in this guide are located in this section. Remember that a code only points to the faulty circuit NOT necessarily to a faulty component. Loose, damaged or corroded connections may contribute to a fault code on a circuit when the sensor or component is operating properly. Be sure that the components are faulty before replacing them, especially the expensive ones. Depending upon the year of your vehicle, it is either On-Board Diagnostic I (OBD I) of On-Board Diagnostic II (OBD II) compliant. All 1994-95 Integras, Legends and Vigors are OBD I compliant. All other models covered by this guide are OBD II compliant. Before beginning any procedure, make sure you have the correct system for your vehicle.
OBD I VEHICLES
When a fault is noted, the ECU (otherwise known as the ECM) stores an identifying code and illuminates the CHECK ENGINE light. The code will remain in memory until cleared; the dashboard warning lamp may not illuminate during the next ignition cycle if the fault is no longer present. Not all faults noted by the ECU will trigger the dashboard warning lamp although the fault code will be set in memory. For this reason, troubleshooting should be based on the presence of stored codes, not the illumination of the warning lamp while the car is operating.
All models are equipped with a service connector in side the cabin of the vehicle. If the service connector is jumped, the CHECK ENGINE lamp will display the stored codes in the same fashion.
The 2-pin service connector is located under the extreme right dashboard on Integra, Legend and 2.5TL on Vigor models, it is found behind the right side of the center console well under the dashboard.
Codes 1-9 are indicated by a series of short flashes; two-digit codes use a number of long flashes for the first digit followed by the appropriate number of short flashes. For example, Code 43 would be indicated by 4 long flashes followed by 3 short flashes. Codes are separated by a longer pause between transaxles. The position of the codes during output can be helpful in diagnostic work. Multiple codes transmitted in isolated order indicate unique occurrences; a display of showing 1-1-1-pause-9-9-9 indicates two problems or problems occurring at different times. An alternating display, such as 1-9-1-9-1, indicates simultaneous occurrences of the faults.
When counting flashes to determine codes, a code not valid for the vehicle may be found. In this case, first recount the flashes to confirm an accurate count. If necessary, turn the ignition switch OFF , then recycle the system and begin the count again. If the Code is not valid for the vehicle, the ECU must be replaced.
See Figures 1 and 2
On vehicles with automatic transaxles, the S, D or D4 lamp may flash with the CHECK ENGINE lamp if certain codes are stored. For Legend this may occur with Codes 6, 7 or 17. On Vigor and Integra it may occur with codes 6, 7 or 13. In addition, the TCS lamp on NSX may flash with codes 3, 5, 6,13,15,16,17, 35 or 36. In all cases, proceed with the diagnosis based on the engine code shown. After repairs, recheck the lamp. If the additional warning lamp is still lit, proceed with diagnosis for that system.
OBD II VEHICLES
Reading the control module memory is one of the first steps in OBD II system diagnostics. This step should be initially performed to determine the general nature of the fault. Subsequent readings will determine if the fault has been cleared.
Reading codes can be performed by either of the methods below:
To read the fault codes, connect the scan tool or tester according to the manufacturer's instructions. Always make sure to follow the manufacturer's specified procedure for reading the codes explicitly.