Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0720: Output Shaft (Countershaft) Speed Sensor Circuit Malfunction
- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
- Information marked with an asterisk (*) applies to '06-08 models.
- This DTC only occurs on M/T vehicles.
- Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.
- Test-drive several miles.
- Check the C SHAFT SPD in the DATA LIST with the HDS.
Is any vehicle speed indicated?
YES -Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM.
NO -Go to step 4.
- Turn the ignition switch OFF.
- Disconnect the output shaft (countershaft) speed sensor 3P connector.
- Turn the ignition switch ON (II).
- Measure voltage between output shaft (countershaft) speed sensor 3P connector terminal No. 1 and body ground.Fig 1: Measuring Voltage Between Output Shaft (Countershaft) Speed Sensor Connector Terminal 1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 5 V?
YES -Go to step 8.
NO -Repair open in the wire between the ECM (A20) and the output shaft (countershaft) speed sensor, then go to step 17.
- Measure voltage between output shaft (countershaft) speed sensor 3P connector terminal No. 2 and body ground.Fig 2: Measuring Voltage Between Output Shaft (Countershaft) Speed Sensor Connector Terminal 2 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 5 V?
YES -Go to step 9.
NO -Go to step 10.
- Measure voltage between output shaft (countershaft) speed sensor 3P connector terminals No. 1 and No. 3.Fig 3: Measuring Voltage Between Output Shaft (Countershaft) Speed Sensor Connector Terminals 1 And 3
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 5 V?
YES -Go to step 15.
NO -Repair open in the wire between the output shaft (countershaft) speed sensor and G101 (ECM (A23))*, then go to step 17.
- Measure voltage between ECM connector terminal A18 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 5 V?
YES -Repair open in the wire between the ECM (A18) and the output shaft (countershaft) speed sensor, then go to step 17.
NO -Go to step 11.
- Turn the ignition switch OFF.
- Jump the SCS line with the HDS.
- Disconnect ECM connector A (31P).
- Check for continuity between ECM connector terminal A18 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Repair short in the wire between the ECM (A18) and the output shaft (countershaft) speed sensor, then go to step 17.
NO -Go to step 24.
- Turn the ignition switch OFF.
- Replace the output shaft (countershaft) speed sensor (see CKP SENSOR REPLACEMENT ).
- Reconnect all connectors.
- Turn the ignition switch ON (II).
- Reset the ECM with the HDS.
- Do the ECM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
- Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR) ('04-05 models), Engine coolant temperature (ECT SENSOR 1) ('06-08 models) above 158°F (70°C)
- Transmission in 5th gear
- Engine speed at 2,000-3,000 rpm
- Drive for several minutes, then decelerate (with the throttle fully closed) for 8 seconds
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0720 indicated?
YES -Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM, then go to step 1.
NO -Go to step 23.
- Monitor the OBD STATUS for DTC P0720 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 22, go to the INDICATED DTCS TROUBLESHOOTING .
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 21.
- Reconnect all connectors.
- Update the ECM if it does not have the latest software (see UPDATING THE ECM/PCM ), or substitute a known-good ECM (see SUBSTITUTING THE ECM/PCM ).
- Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR) ('04-05 models). Engine coolant temperature (ECT SENSOR 1) ('06-08 models) above 158°C (70°C)
- Transmission in 5th gear
- Engine speed at 2,000-3,000 rpm
- Drive for several minutes, then decelerate (with the throttle fully closed) for 8 seconds
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0720 indicated?
YES -Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM. If the ECM was updated, substitute a known-good ECM (see SUBSTITUTING THE ECM/PCM ), then go to step 26. If the ECM was substituted, go to step 1.
NO -Go to step 28.
- Monitor the OBD STATUS for DTC P0720 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM; '04-05 models (see ECM/PCM REPLACEMENT ), '06-08 models (see '06-08 MODELS ). If any other Temporary DTCs or DTCs were indicated in step 27, go to the INDICATED DTCS TROUBLESHOOTING .
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM. If the ECM was updated, substitute a known-good ECM (see SUBSTITUTING THE ECM/PCM ), then go to step 26. If the ECM was substituted, go to step 1. If the screen indicates NOT COMPLETED, go to step 26.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.