P24D5

Code

Generic P — Powertrain

EVAP System Pressure Sensor/Switch B Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 19 EN: 27 RU: 19

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Page language: EN

Causes

Open or short in sensor harness (B circuit)
Corroded, loose, or damaged connector at sensor
Failed EVAP pressure sensor/switch (B)
Poor sensor ground or reference voltage issue
Intermittent wiring fault due to chafing or heat
PCM/ECM internal input fault (less common)

Symptoms

Malfunction Indicator Lamp (MIL) or Check Engine light illuminated
Possible EVAP system leak/venting restrictions or reduced EVAP functions
Difficulty completing EVAP monitor or failed readiness test
Rarely, drivability issues if PCM limits engine operation

What to check

Read freeze frame and related EVAP codes; record live data for EVAP pressure B
Visual inspection of sensor, connector, and wiring for damage, corrosion, or contamination
Backprobe sensor connector and measure signal voltage with key ON and engine OFF/ON
Measure reference voltage (usually 5 V) and ground continuity at sensor connector
Wiggle test wiring while monitoring signal for intermittent faults
Compare sensor B readings to sensor A (if fitted) or to expected values

Signal parameters

Typical sensor output: 0–5 V analog proportional to pressure (many systems ~0.5–4.5 V across operating range)
Fault detection thresholds: signal < ~0.1 V suggests short to ground/open; signal > ~4.9 V suggests short to battery
Signal should change smoothly with applied vacuum/pressure; abrupt jumps or no change indicate sensor/wiring fault
Reference supply typically ~5 V (verify exact value on vehicle)
Expected response: gradual, monotonic change when applying vacuum/pressure (no erratic spikes)

Diagnostic algorithm

Capture freeze-frame and live-data for this and related EVAP codes. Note conditions when fault set.
Visually inspect EVAP pressure sensor B, connector, and wiring for damage, corrosion, or contamination.
With key ON, backprobe the sensor connector: verify reference voltage, ground, and signal at rest. Compare to expected values.
Apply vacuum or pressure to the EVAP sensor port while monitoring signal. Confirm smooth, proportional change in voltage.
Perform wiggle tests along the harness while monitoring live data to detect intermittent opens/shorts.
If low/high/erratic signals present, disconnect sensor and check for open/short to power or ground at harness with multimeter (pin-to-pin/ground).
If wiring and connector test good, substitute a known-good sensor or bench-test the suspect sensor per manufacturer procedure.
Repair or replace damaged wiring/connectors or replace the sensor as indicated. Clear codes and confirm repair by road test and checking EVAP monitor readiness.
If wiring and sensor check good but fault persists, investigate ECU input and grounds or consult OEM technical service information for PCM diagnostics.

Likely causes

Wiring harness rubbed through and shorting to chassis or power
Connector pins corroded or pushed back in terminal
Sensor contaminated by liquid or debris and failed
Short to battery voltage or short to ground on signal wire
Ground or reference (5 V) circuit open or weak

Fault status

⚠️ Status

EVAP system pressure sensor/switch B circuit fault detected. PCM has identified an out-of-range, short, open, or intermittent signal on the EVAP pressure B input. As a result, EVAP functions may be limited and MIL is/was commanded on.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours