Check for continuity between ECM/PCM connector terminal A20 and body ground. ECM/PCM CONNECTOR A (31P) Wire side of female terminals Is there continuity? YES - Repair short in the wire between the ECM/PCM (A20) and the EGR valve position sensor, knock sensor or TP sensor, or repair short in the wire between the ECM/PCM (A8) and the knock sensor. NO - Substitute a known-good ECM/PCM and recheck, refer to the '01 Civic Shop Manual on this CD (see page 11-6). If symptom/indication goes away, replace the original ECM/PCM.

Turn the ignition switch OFF. Connect a scan tool/Honda PGM Tester, refer to the '01 Civic Shop Manual on this CD (see page 11-3). Turn the ignition switch ON (II) and read the scan tool/Honda PGM Tester. Does the scan tool/Honda PGM Tester communicate with the ECM/PCM? YES - Go to step 70. NO - Go to step 66. Turn the ignition switch OFF. Disconnect ECM/PCM connector E (31P). Check for continuity between body ground and Data Link Connector (DLC) terminal No. 7. DATA LINK CONNECTOR (DLC) Terminal side of male terminals Is there continuity? YES - Repair short in the wire between the DLC and the ECM/PCM (E23). After repairing it, check the DTC with the scan tool/Honda PGM Tester and go to the DTC Troubleshooting Index. NO - Go to step 69.