What this code means
P0533 may mean the ECM or PCM is seeing the A/C pressure sensor circuit signal as high.
What the vehicle may do
- The A/C may not operate normally.
- Cooling may be limited or inconsistent.
- The condition can be intermittent if the high reading is not present during testing.
Possible fault areas
- A/C pressure sensor or sensor connection
- Poor terminals or loose connections at the A/C pressure sensor or PCM
- Possible open in the PD_SENSOR signal line
- Possible open in the SG6 line
- Possible PCM software or PCM concern after the circuit checks pass
Diagnostic path
Opening context
On this 2010 to 2015 Honda Civic with the 1.8 gas engine, P0533 means the ECM or PCM is seeing the A/C pressure sensor circuit reading high. In plain terms, the computer may be seeing a pressure sensor signal that is too high for the circuit condition. The driver may notice the A/C does not operate normally or cooling may be limited. The possible fault areas can include the A/C pressure sensor, its connector or terminals, the signal and ground-side wiring, the reference circuit, or, after the circuit checks pass, a possible PCM software or PCM issue. Before getting deep into the circuit, start with the basic system checks and follow a structured diagnostic approach. If captured operating data is available, try to reproduce the problem under those same conditions.
Verify the fault is present
Start by duplicating the problem. Start the engine and let it idle. Turn the blower switch on, then turn the A/C switch on. With the HDS, watch A/C PRESSURE SENSOR in the data list. If the reading is about 4.75 V or more, the failure is duplicated and you continue into the circuit checks. If it is not about 4.75 V or more, treat it as an intermittent condition for now. At that point, the system is OK at this time, so check for poor connections or loose terminals at the A/C pressure sensor and at the PCM.
Simulate the sensor side of the circuit
Next, separate the sensor from the rest of the circuit. Turn the ignition switch to LOCK (0), or select OFF mode. Disconnect the A/C pressure sensor 3P connector. Install a jumper wire between terminal A and terminal B: terminal A is A/C pressure sensor 3P connector No. 1, BLK, and terminal B is A/C pressure sensor 3P connector No. 2, LT GRN. Then turn the ignition switch to ON (II), or select ON mode, and check A/C PRESSURE SENSOR in the HDS data list again. If it still shows about 4.75 V or more, keep going. If it does not, replace the A/C pressure sensor.
Check the SG6 and VCC6 voltage
Now remove that jumper and check the sensor connector voltage. Turn the ignition switch back to LOCK (0), or OFF mode, remove the jumper wire, then turn the ignition switch to ON (II), or ON mode. With the A/C pressure sensor 3P connector still disconnected, measure between the SG6 and VCC6 test points: test point 1 is A/C pressure sensor 3P connector No. 1, BLK, and test point 2 is A/C pressure sensor 3P connector No. 3, RED. You are looking for about 5.0 V. If you have about 5.0 V, move to the PD_SENSOR open-circuit check. If you do not, move to the SG6 open-circuit check.
Check the PD_SENSOR wire for an open
For the PD_SENSOR line, turn the ignition switch to LOCK (0), or OFF mode. Jump the SCS line with the HDS, then disconnect PCM connector A, the 51P connector. With the A/C pressure sensor 3P connector disconnected and PCM connector A disconnected, check continuity between PCM connector A No. 27, LT GRN, and A/C pressure sensor 3P connector No. 2, LT GRN. If there is continuity, the PD_SENSOR wire is OK. At that point, update the PCM if it does not have the latest software, or substitute a known-good PCM. If P0533 goes away after the update, troubleshooting is complete. If P0533 goes away with the known-good PCM substituted, replace the original PCM. If there is no continuity, repair the open in the PD_SENSOR wire between PCM A27 and the A/C pressure sensor.
Check the SG6 wire for an open
If the earlier voltage check sent you to the SG6 side, the setup is similar. Turn the ignition switch to LOCK (0), or OFF mode. Jump the SCS line with the HDS, then disconnect PCM connector A, the 51P connector. With the A/C pressure sensor 3P connector disconnected and PCM connector A disconnected, check continuity between PCM connector A No. 10, BLK, and A/C pressure sensor 3P connector No. 1, BLK. If there is continuity, the SG6 wire is OK. Then update the PCM if it does not have the latest software, or substitute a known-good PCM. If P0533 goes away after the update, troubleshooting is complete. If P0533 goes away with the known-good PCM substituted, replace the original PCM. If there is no continuity, repair the open in the SG6 wire between PCM A10 and the A/C pressure sensor.
Final takeaway
The key on P0533 is not to condemn the sensor just because the code name mentions pressure. Verify the high reading first, simulate the sensor circuit, then use the voltage and continuity checks to decide whether the fault is in the sensor, the PD_SENSOR line, the SG6 line, or the PCM side after the wiring proves good. Keep verification separate from testing, and confirm the code stays gone under the conditions that originally brought it in. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0533 is best approached as an electrical sensor-circuit diagnosis: verify the high signal, simulate the sensor side, then follow the voltage and continuity results before making a repair decision.
For more guided automotive diagnostics, visit STEP Diagnostics.
