What this code means
P24C0 may indicate that the PCM is seeing EVAP leak check pressure behavior that does not look correct for the canister change over valve close function.
What the vehicle may do
- The check engine light may be on.
- The EVAP monitor may not complete.
- The vehicle may have little or no noticeable drivability change.
Possible fault areas
- Possible EVAP leak check module concern.
- Possible canister one way valve or drain path concern.
- Possible hose, connection, or routing concern.
- Possible pressure interpretation concern in the EVAP leak check system.
Diagnostic path
Opening context
On this 2017 to 2025 Honda CR-V with the 1.5 turbo engine, P24C0 is a canister change over valve close malfunction in the EVAP leak check system. In plain language, the PCM is watching pressure information from the ELCM side of the EVAP system, and this code may set when that pressure behavior does not look plausible. The vehicle may have a check engine light, may have an EVAP monitor that will not complete, and often may not have a strong drivability complaint. The broad possible fault areas can include the EVAP leak check module area, the canister one way valve and drain path, hoses or connections, or how the PCM is interpreting the pressure signal. Before chasing the code, start with the basic system checks and keep the diagnostic path structured.
What the PCM is reacting to
The logic behind P24C0 is pressure plausibility. The PCM calculates relative pressure from the ELCM pressure sensor value. If that calculated pressure is lower than the specified value, the PCM judges the condition abnormal and stores P24C0. So the goal here is not to guess at a part first. The goal is to reproduce the operating conditions, then check whether the EVAP leak check path behaves the way it should.
Confirmation routine
Start the engine and let it idle with no load, in Park or Neutral, until the radiator fan comes on. That gets the system into the right monitor gate before you judge the code.
Hold the commanded purge condition
Next, watch EVAP PC Duty on the HDS. Hold engine speed at 3,000 rpm with EVAP PC Duty at 20 % or more for at least 4 minutes, then let the engine return to idle. Keep this part clean and controlled, because this is where you are trying to recreate the condition the PCM needs in order to run the check.
Check the code status
Now monitor OBD STATUS for P24C0 on the HDS. Treat this confirmation routine as the code check. Do not mix it together with the pressure test; finish confirming the code status first, then move into component-side testing.
Pressure test setup at the drain tube
For the test procedure, disconnect the drain tube from the EVAP leak check module. Then connect a hose to the drain tube, and connect a 0-30 inHg vacuum pump and gauge to that hose. The connection layout is position-specific, so identify the EVAP leak check module, drain tube, and test hose routing carefully before applying pressure. If the exact connection point is not clear on the vehicle, pause and recheck the setup instead of guessing.
Apply pressure at the drain tube
With the gauge connected to the drain tube setup, apply pressure to the hose. This step is part of isolating the drain-side path before moving the gauge to the canister one way valve.
Move the gauge to the canister one way valve
Disconnect the hose from the drain tube. Then connect the hose to the canister one way valve, and connect the 0-30 inHg vacuum pump and gauge to the hose. Again, make sure the hose is on the correct valve connection before you apply pressure.
Judge the pressure result
Apply pressure to the hose. The normal result is that pressure is not held. If that result is abnormal, the diagnostic path points to a problem in the ELCM system. If the result is normal, the diagnostic path points back to a problem with the EVAP leak check module. Stay with that split, and do not jump ahead to a part decision that the test did not support.
Close
The key with P24C0 is to separate confirmation from testing: warm the vehicle, reproduce the commanded purge condition, confirm the code status, then use the pressure checks to decide which side of the EVAP leak check system the fault path is pointing toward. For more diagnostic training, visit stepdiagnostics.com.
Final check
P24C0 is best handled by confirming the code under the proper operating conditions, then using the pressure behavior to separate an ELCM system-side issue from an EVAP leak check module-side issue.
For more guided automotive diagnostics, visit STEP Diagnostics.
