DTC P24B9

DTC P24B9:  Evaporative Emission (EVAP) Leak Check Module Pressure Sensor Range/Performance Problem

General Description 

Courtesy of HONDA, U.S.A., INC.

The fuel vapor in the fuel tank is temporarily stored in the evaporative emission (EVAP) canister and drawn into the engine through the EVAP canister purge valve. The powertrain control module (PCM) controls the amount of vapor introduced into the engine by varying the duty cycle of the EVAP canister purge valve according to the condition of the engine. While purge control is stopped, the EVAP leak check module pressure sensor output is a pressure equivalent to the atmospheric pressure. If the difference between the barometric pressure (BARO) sensor pressure and EVAP leak check module pressure sensor pressure exceeds the specified value for a set time, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type 

Enable Conditions 

Malfunction Threshold 

When a difference in pressure of the leak detection sensor and the BARO sensor became more than 17 kPa (125 mmHg, 4.9 inHg).

Possible Cause 

NOTE:  The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

• BARO sensor range/performance problem
• EVAP leak check module pressure sensor range/performance problem
• Manifold absolute pressure (MAP) sensor range/performance problem
• Purge control solenoid failure
• Air cleaner element clogged
• Valve timing incorrect
• Throttle body air leak
• Intake manifold air leak

Confirmation Procedure 

Operating Condition 

Courtesy of HONDA, U.S.A., INC.

• Enter the maintenance mode, then start the engine. Hold the engine speed [Engine Speed] at 3, 000 rpm without load (in P or N) until the radiator fan comes on.
• Let the engine idle for at least 18 seconds.
• Drive the vehicle at engine speed [Engine Speed] 4, 000 rpm or more with throttle position 29.6 deg. or more for at least 2.5 seconds.
• Decelerate with the throttle valve fully closed for at least 8 seconds.

• When freeze data is stored, drive the vehicle under those conditions instead of Driving Pattern step 4.
• Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details 

Conditions for setting the DTC 

When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC 

The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool clear command or by disconnecting the 12 volt battery.