P24BA: EVAP System Leak Detection Pump Pressure Sensor Circuit Low

P24BA reports that the voltage from the leak check module's pressure sensor has fallen below the lowest value a working sensor can produce. In GM's ELCP tables (2018 Volt) the limit is 0.70 V, about 14 % of the reference or roughly 47 kPa absolute, with 640 failures in 800 samples taken every 12.5 ms; the check runs whenever the controller is awake and is Type B. Mitsubishi's 2023 Outlander PHEV sets P24BA when the signal stays under 0.1 V for 2 s. Subaru asks technicians to clear P24BA before chasing P2404 in the ELCM. A low signal mostly means a lost 5 V reference, a signal wire shorted to ground or a dead sensor. P24BB is the high-side counterpart; the leak test is suspended until the fault is gone.

Symptoms

• Malfunction indicator lamp on
• EVAP leak test not run

Most likely causes

• Sensor signal wire shorted to ground
• 5 V reference open or pulled down by another sensor on the same supply
• Pressure sensor inside the leak check module failed

What to check, in order

Start with the simplest. You can tick off each step.

1. Start with the fuel cap: tighten it fully and check its seal
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Inspect the hoses and connections around the tank and the charcoal canister
4. Use the scanner to test the purge and vent solenoid valves
5. Run a smoke test to find small leaks

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P24BA means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 4: Emissions
• BA: Specific fault in that system

Frequently asked questions

Can I keep driving with code P24BA?

Yes, you can normally keep driving. If there is a strong smell of gasoline, find the leak before continuing and do not smoke nearby.

What causes code P24BA?

The most common causes are: sensor signal wire shorted to ground; 5 V reference open or pulled down by another sensor on the same supply; pressure sensor inside the leak check module failed.

Related codes

• P24BBEVAP System Leak Detection Pump Pressure Sensor Circuit High
• P24B9EVAP System Leak Detection Pump Pressure Sensor Circuit Range/Performance
• P24B8EVAP System Leak Detection Pump Pressure Sensor Circuit
• P24BCEVAP System Leak Detection Pump Pressure Sensor Circuit Intermittent
• P2404EVAP System Leak Detection Pump Sense Circuit Range/Performance

Sources

• gsi.ext.gm.com: 18OBDG01 Hybrid Diagnostics
• mitsubishitechinfo.com: N502424280000800USA
• static.nhtsa.gov: MC 10240115 0001

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.