P24B8

Code

Generic P — Powertrain

EVAP System Leak Detection Pump Pressure Sensor Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 19 EN: 36 RU: 26

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Page language: EN

Causes

Open or short in pressure sensor signal wire
Poor or corroded connector or terminal at the pressure sensor or ECM
Faulty EVAP leak detection pump pressure sensor
Failed or intermittent ground or 5 V reference to the sensor
Faulty EVAP leak detection pump (mechanical/electrical) causing invalid readings
Blown fuse, faulty relay, or power supply issue to pump/sensor circuit

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
EVAP system test or readiness failure; EVAP self-test may not complete
Possible fuel odor from vehicle if EVAP system not sealed
No EVAP leak detection pump activity when commanded or abnormal pump behavior
Failed state or restricted refueling/inspection readiness

What to check

Read DTCs and freeze frame with a scan tool; note related EVAP codes
Attempt EVAP leak detection pump self-test and watch live data for pressure sensor response
Visually inspect wiring harness and connectors for damage, corrosion, pin damage, or moisture
Back-probe pressure sensor connector: verify 5 V reference (if used), sensor ground continuity, and signal voltage while commanding pump on/off
Measure resistance/continuity between sensor ground and chassis ground; check for shorts to battery +
Command pump on with scan tool and confirm pump electrical current draw and that the pressure signal changes as expected

Signal parameters

Sensor supply/reference: typically 5.0 V reference (verify factory spec)
Sensor ground: near 0 V, continuity to chassis ground expected (
Signal voltage at rest: often near low end (~0.5 V) and increases with pressure/vacuum; expected working range commonly ~0.5–4.5 V (manufacturer-specific)
When pump commanded, signal should change smoothly and proportionally to created pressure; abrupt jumps, stuck value, open (≈floating voltage), or short to 0 V/ battery + are faults

Diagnostic algorithm

Use a scan tool: read and record DTCs, freeze frame, and live PIDs related to EVAP pump and pressure sensor. Clear codes and attempt to re-run EVAP test to reproduce.
Command the EVAP leak detection pump ON while monitoring the pressure sensor signal PID. Note whether the signal changes logically with pump operation.
Inspect the sensor/pump module connector and wiring for corrosion, pin damage, moisture ingress, or chafing. Repair any visible damage.
Back-probe the connector: with ignition ON (or as specified), verify 5 V reference present, good ground, and measure signal voltage. Compare with expected values from manufacturer data.
With pump commanded ON, measure signal behavior and pump current draw. High or no current indicates pump motor issue; fixed or implausible signal indicates sensor/wiring problem.
Perform continuity checks from the sensor signal and ground pins back to the ECU/PCM connector. Check for short to battery + or ground.
If wiring, power and grounds test good but signal is still out of range, remove and bench-test or replace the pressure sensor or the leak detection pump assembly per OEM procedure.
After repair, clear codes and repeat EVAP self-test. Confirm absence of DTC, correct sensor response, and EVAP readiness. If problem persists, consider module/ECU diagnosis or reprogramming as a last resort.

Likely causes

Damaged/shorted wiring between pressure sensor and ECM
Corroded/loose connector at the pressure sensor or pump module
Failed pressure sensor inside the leak detection pump assembly
Poor ground at sensor or pump module

Fault status

⚠️ Status

The engine control module detected an electrical fault or implausible reading from the EVAP leak detection pump pressure sensor circuit. Verify wiring, connectors, sensor and pump operation before replacing parts.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 3.0 hours