What this code means
P0842 may indicate that the CVT control system is seeing a low signal from the transmission fluid pressure sensor/switch A circuit, often tied to the driven pulley pressure sensor.
What the vehicle may do
- The vehicle may set a warning light or store the code without an obvious driveability complaint.
- CVT operation may feel abnormal if the control system is reacting to an unreliable pressure signal.
Possible fault areas
- Possible sensor signal circuit problem
- Possible sensor feed circuit problem
- Possible pressure sensor issue
- Possible PCM software or PCM-side issue after circuit checks
Diagnostic path
Opening context
On this 2010 to 2015 Honda Civic with the CVT, P0842 means the control side is seeing the transmission fluid pressure sensor/switch A signal low. In plain terms, we’re working around the driven pulley pressure sensor signal. The vehicle may have CVT operation complaints or may simply set the code, and the broad fault areas can include the sensor circuit, the sensor feed, the sensor itself, or the PCM side after the wiring is ruled out. The important point before chasing hydraulic or internal transmission problems is this: this code is called out as an electrical circuit problem, not a mechanical problem inside the transmission.
Confirm the problem first
Start with the basic system checks, then verify the fault. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode. Clear the DTC with the HDS, then watch Driven Pulley Pressure Sensor(V) in the HDS Data List. If it reads 0.21 V or less, the failure is duplicated and you move into circuit isolation. If it does not read 0.21 V or less, treat it as intermittent for now. The system is OK at this time, and if captured data or an on-board snapshot is available, try to reproduce the same operating conditions before making a call.
Separate the sensor from the rest of the circuit
Next, narrow down whether the low reading is being pulled down on the PDN line or whether the problem is somewhere else. Turn the ignition switch to LOCK (0), or select OFF mode. Disconnect the CVT driven pulley pressure sensor 3P connector. Then turn the ignition switch back to ON (II), or select ON mode, and check Driven Pulley Pressure Sensor(V) again in the HDS Data List. If it still reads 0.21 V or less with the sensor disconnected, go after a short to ground on the PDN line. If it no longer reads that low, move to the VCC2 feed check.
Check the PDN line for a short to ground
For the PDN short check, turn the ignition switch to LOCK (0), or select OFF mode. Jump the SCS line with the HDS, then disconnect PCM connector B (51P). With the CVT driven pulley pressure sensor 3P connector disconnected and PCM connector B (51P) disconnected, check continuity between the CVT driven pulley pressure sensor 3P connector No. 2, the BLU/RED wire, and body ground. If there is continuity, repair the short to ground in the PDN wire between the driven pulley pressure sensor and the PCM. If there is no continuity, the PDN wire is OK. At that point, update the PCM if it does not have the latest software, or substitute a known-good PCM and recheck. If P0842 goes away after the PCM update, the troubleshooting is complete. If P0842 goes away with the known-good PCM substituted, replace the original PCM.
Check the VCC2 feed and decide on the sensor branch
If the earlier sensor-disconnected check did not stay at 0.21 V or less, check the VCC2 line. Measure voltage between the CVT driven pulley pressure sensor 3P connector No. 3, the YEL/BLU wire, and body ground. The listed test condition is IG ON (II) or ON mode, with the CVT driven pulley pressure sensor 3P connector disconnected and PCM connector B (51P) disconnected. If the measurement is about 5 V, the VCC2 wire is OK, and the diagnostic path calls for replacing the CVT driven pulley pressure sensor. If it is not about 5 V, repair the open in the VCC2 wire between the driven pulley pressure sensor and the PCM.
Verification and takeaway
Keep the confirmation separate from the testing. After the indicated repair or PCM software path, recheck P0842 before calling the job done. The takeaway is simple: prove the low sensor reading first, unplug the sensor to split the fault path, then follow the result into either the PDN short check or the VCC2 feed check. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnostic is mainly about proving whether the low signal is present, then separating a wiring fault from a sensor or PCM-side path.
For more guided automotive diagnostics, visit STEP Diagnostics.
