P24D7

Code

Generic P — Powertrain

EVAP System Pressure Sensor/Switch B Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 19 EN: 75 RU: 26

AI status

Completed

ready

Completed 100%

Page language: EN

Short to ground in the EVAP pressure sensor B signal circuit
Open or high-resistance wiring or connector (broken wire, corrosion, poor pin contact)
Faulty EVAP system pressure sensor / pressure switch B
Missing or bad reference voltage or ground to the sensor
Intermittent connection or water intrusion at connector
Faulty PCM/ECM driver or internal circuit fault (less common)

MIL (Check Engine Light) ON
Failed EVAP readiness or leak-check tests
Possible difficulty completing EVAP system self-test (long crank or drivability not typical)
Rarely: noticeable fuel odor if EVAP system disabled, but often no obvious drivability change

Read and record freeze frame and all stored/related DTCs with a scan tool
Monitor live data: EVAP pressure sensor B signal, reference voltage, and sensor ground
Visually inspect sensor connector and wiring for damage, corrosion, or water
Perform wiggle test on harness while monitoring live data for intermittent changes
Backprobe sensor connector and measure voltages with key on (engine off) — compare to expected
Check continuity from sensor pins to ECM and for shorts to ground or battery

Reference supply (typical): ~5.0 V (check vehicle spec)
Sensor signal normal range (typical): ~0.5–4.5 V proportional to pressure — varies by vehicle
Low-logic/failed threshold: signal near 0.0–0.2 V may set a 'low' DTC
Ground continuity: near 0 ohms between sensor ground pin and chassis/ECM ground
Wiring resistance: low and stable; high resistance (> a few ohms) indicates problem

Verify DTC: connect scan tool, read code P24D7 and any related EVAP codes. Record freeze frame and PID data.
Inspect: locate EVAP pressure sensor B and visually inspect connector/harness for corrosion, damage, or signs of water intrusion.
Check reference and ground: backprobe sensor connector with key ON (engine off). Verify reference voltage (≈5V) and good ground. If reference missing, trace to fuse/ECM.
Measure signal: with key ON or engine running per service data, measure sensor signal voltage. If signal is very low (
Wiggle/backprobe test: wiggle harness and connector while watching live data for intermittent changes. Repair any intermittent wiring.
Continuity and shorts: disconnect sensor and check continuity from signal, reference and ground pins to the ECM. Check for short to ground or battery on the signal circuit.
Sensor bench/functional test: if wiring and voltages are good, substitute a known-good sensor or bench-test the suspect sensor per manufacturer procedure.
Repair: repair wiring, clean/replace connector, or replace the sensor as needed. If wiring/connector repair performed, retest for proper voltages and continuity.
Clear codes and test drive: erase codes, run EVAP leak/monitor tests or complete required drive cycle. Verify the code does not return.
ECM check: if all wiring and sensor tests are good and the fault persists, consider ECM/PCM diagnosis (rare) or consult manufacturer service information.