What this code means
P0722 may indicate that the PCM is not receiving the expected output shaft, or countershaft, speed signal.
What the vehicle may do
- The vehicle may show abnormal shift behavior.
- A warning light may be present.
- The complaint can often be speed-related because the PCM uses shaft speed information for transmission control.
Possible fault areas
- Possible output shaft speed sensor circuit issue.
- Possible poor connection or loose terminal at the sensor or PCM side.
- Possible concern in the sensor power, signal, or ground wiring.
- Possible output shaft speed sensor fault.
Diagnostic path
Opening context
On this Accord, P0722 may mean the PCM is not seeing the output shaft, or countershaft, speed signal the way it expects. The driver may notice abnormal shift behavior, speed-related transmission complaints, or a warning light. Broadly, this can involve the output shaft speed sensor circuit, the sensor connection, the sensor power, signal, or ground side, or the sensor itself. Before getting deep into testing, start with the basic system checks. For this code path, keep the diagnosis electrical. This code is not treated as a mechanical transmission problem.
Duplicate the problem first
Start by turning the vehicle to the ON mode and clearing the DTC with the HDS. Raise the vehicle on a lift, make sure it is securely supported, and make sure all four wheels can rotate freely. Start the engine, then disable VSA by pressing the VSA OFF button. If vehicle speed will be above 31 mph (50 km/h), enter VSA maintenance mode.
Compare shaft speeds
With the vehicle in D position or mode, run it at speeds over 12 mph (20 km/h). On the HDS, compare Input Shaft, or Mainshaft, Speed rpm against Output Shaft, or Countershaft, Speed rpm. Then slow down and stop the wheels. If the two speeds are about the same, treat it as an intermittent failure for now. The system is OK at this time, so check for poor connections and loose terminals between the output shaft speed sensor and the PCM. If captured data for this DTC is available, try to reproduce the same operating conditions. If the speeds are not about the same, the failure is duplicated and you move into circuit testing.
Check the VCC1 supply
For the VCC1 open-wire check, turn the vehicle to the OFF, LOCK, mode. Disconnect the output shaft, or countershaft, speed sensor 3P connector, then turn the vehicle back to the ON mode. Measure voltage on the VCC1 circuit between output shaft speed sensor 3P connector No. 3, the PNK wire, and body ground. You are looking for about 5 V. If you have about 5 V, the VCC1 wire is OK and you continue. If you do not have about 5 V, repair an open in the VCC1 wire between the output shaft speed sensor and the PCM.
Check the NC signal voltage
Next, with the vehicle still in the ON mode and the output shaft speed sensor 3P connector disconnected, measure the NC circuit voltage between connector No. 2, the TAN wire, and body ground. This check should show about 5 V. If it does, continue to the SG1 ground-side check. If it does not, skip ahead to the NC shorted-wire check.
Check the SG1 ground path
For the SG1 open-wire check, turn the vehicle to the OFF, LOCK, mode. With the output shaft speed sensor 3P connector still disconnected, check continuity between connector No. 1, the BLU wire, and body ground. If there is continuity, the SG1 wire is OK, and this path calls for replacing the output shaft, or countershaft, speed sensor. If there is no continuity, repair an open in the SG1 wire between the output shaft speed sensor and the PCM.
Check the NC circuit for a short or open
If the NC voltage check did not show about 5 V, turn the vehicle to the OFF, LOCK, mode. Jump the SCS line with the HDS, then disconnect PCM connector C, 51P. With the output shaft speed sensor 3P connector disconnected and PCM connector C disconnected, check continuity between the NC circuit at connector No. 2, the TAN wire, and body ground. If there is continuity, repair a short to body ground in the NC wire between the output shaft speed sensor and the PCM. If there is no continuity, the NC wire is not shorted, so repair an open in the NC wire between the output shaft speed sensor and the PCM.
Takeaway
The takeaway is simple: on this P0722 path, do not chase internal transmission mechanics. Prove the speed comparison first, then work the electrical side in order: VCC1 supply, NC signal behavior, SG1 ground, and finally the NC short-or-open decision. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnosis should stay focused on proving the electrical speed-sensor signal path in order.
For more guided automotive diagnostics, visit STEP Diagnostics.
