Honda B16A ECU Error Codes

The table below lists the ECU error codes that can be thrown by a Honda B16A ECU. These codes have been copied directly from a Honda Service Manual. I can't remember which year Honda it was for, but I think it was for a 5th generation Honda Civic.

How to Obtain ECU Error Codes - How to Reset ECU Error Codes

These error codes are very useful for determining the cause of any problems that you may have, for example after doing a B16A Engine Swap, Ford XF Throttle Body Swap or for general maintenance purposes.

Honda ECU Diagnostic Trouble Codes
Diagnostic Trouble Code (DTC) System Indicated
0 Engine Control Module (ECM)
1 Heated Oxygen Sensor (HO2S)
3 Manifold Absolute Pressure (MAP Sensor)
4 Crankshaft Position (CKP Sensor)
6 Engine Coolant Temperature (ECT Sensor)
7 Throttle Position (TP Sensor)
8 Top Dead Center Position (TDC Sensor)
9 No. 1 Cylinder Position (CYP Sensor)
10 Intake Air Temperature (IAT Sensor)
13 Barometric Pressure (BARO Sensor)
14 Idle Air Control (IAC Valve)
15 Ignition Output Signal
16 Fuel Injector
17 Vehicle Speed Sensor (VSS)
20 Electrical Load Detector (ELD)
21 Variable Valve Timing & Valve Lift Electronic Control Solenoid Valve (VTEC Solenoid Valve)
22 Variable Valve Timing & Valve Lift Electronic Control Pressure Switch (VTEC Pressure Switch)
23 Knock Sensor (KS)
30 A/T FI Signal A
31 A/T FI Signal B
41 Heated Oxygen Sensor (HO2S) Heater
43 Fuel Supply System

How to Obtain ECU Error Codes

To determine if your ECU has an error code:

  1. Locate the ECU under the carpet in the passenger foot well.
  2. Find the red LED in the center of the ECU.
  3. Turn the ignition to ON. The red LED should flash once when this happens to indicate that the ECU has power.
  4. If there are no further flashes then there are no error codes.
  5. If there are further flashes then there are one or more error codes.

To get the number of the stored error code you need to count the number of long flashes and the number of short flashes. The long flashes will occur before the short ones. A long flash represents 10, and a short flash indicates 1. So if the flashes look like _ _ - - (where _ is a long flash and - is a short one) then the error code is 22.

If there are mulitple error codes, then there will be a noticeable pause before the next code starts. If for some reason you end up with an error code that is not on the list above, make sure you are not joining together flashes from two separate error codes. If you are sure about the error code and it is not above, then perhaps do a search for other Honda ECU error codes. The entire list is longer than above for engines other than first generation B16A engines.

How to Reset ECU Error Codes

To reset the error codes stored in the ECU you pretty much need to disconnect the battery. This is the only way I have managed to do it thus far. Apparently you can remove the ECU fuse in the engine bay and the clock fuse in the cabin to reset it, but I haven't had a chance to test it yet even though I got the Fuse Panel Translation months ago. Removing the ECU fuse in the engine bay alone does not reset the error codes no matter how long you leave it out.

Note that error codes remain in the ECU until they are reset, even if the problem gets fixed or mysteriously goes away.