Coolant Temperature Gauge Needle Goes Past the Hot Mark

Check for fuel and emissions related DTCs.
If you find any, repair the problem, and clear the DTC before continuing.
Turn the ignition switch OFF, and disconnect PCM 32P connector A.
Turn the ignition switch ON (II), and watch the coolant temperature gauge.
Does the temperature gauge needle stay on the cold mark? (You may have to watch it for about 60 seconds.)
1. YES - Substitute a known-good PCM and recheck, (see HOW TO SUBSTITUTE THE PCM FOR TESTING ). If the symptom/indication goes away, replace the original PCM.
2. NO - Go to step 4.
Turn the ignition switch OFF, and disconnect gauge assembly 30P connector A.
Check for continuity between PCM 32P connector A No. 31 terminal and body ground.

Fig 1: Checking For Continuity Between PCM 32P Connector A No. 31 Terminal & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Repair short to ground between PCM 32P connector A No. 31 terminal and gauge assembly 30P connector A No. 29 terminal.
2. NO - Replace the gauge assembly.