Code
P1405
LAND ROVER
P — Powertrain
Upstream Manta of the Delta pressure sensor disconnected or connected
Views:
UK: 6
EN: 10
RU: 6
AI status
Completed
Completed
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Causes
- Damaged or disconnected sensor connector
- Broken, corroded or shorted wiring in the sensor circuit
- Failed upstream delta/differential pressure sensor
- Vacuum/pressure hose disconnected, collapsed or blocked (if external hoses are used)
- Poor ground or power supply to the sensor
- ECM input fault (rare)
Symptoms
- Check Engine Light (MIL) ON
- Reduced engine performance or derate in some conditions
- Erratic idle or stalling in some cases
- Possible increased emissions or failed emissions test
- Diagnostic trouble code P1405 stored in ECM
What to check
- Visually inspect the delta/differential pressure sensor and wiring harness for damage, corrosion, loose pins, or disconnected hoses
- Use a scan tool to read live sensor data and confirm values change with engine load/pressure events
- Check for related stored codes (EGR, MAP, vacuum, or ECM communication faults)
- Perform wiggle test on wiring while monitoring live data to reproduce fault
- Measure sensor supply voltage and ground at the connector with key on (engine off)
- Measure sensor output voltage while varying intake/EGR pressure if safely possible
Signal parameters
- Typical differential pressure sensor output: ~0.5–4.5 V across operating range (zero differential near center ~2.5 V) — manufacturer-specific limits may vary
- Supply voltage to sensor typically battery voltage or regulated 5 V (check vehicle spec)
- Expected output change when applying known differential pressure (voltage should move smoothly without dropouts)
- Open-circuit: sensor output may float to near 0 V or battery voltage; short-to-ground or short-to-rail will show near 0 V or near supply voltage respectively
Diagnostic algorithm
- Retrieve freeze frame and all stored codes; note conditions when P1405 set.
- Perform a visual inspection of the sensor, connector, wiring harness, and any related vacuum/pressure hoses for disconnection, damage, or contamination.
- With ignition ON (engine off), measure sensor supply voltage and ground at the connector. Confirm correct supply (refer to vehicle spec, commonly 5 V) and good ground.
- Back-probe the sensor signal wire and observe voltage with scan tool or multimeter. At rest (zero differential) expect a mid-range voltage (~2.5 V).
- While monitoring live data, gently apply pressure/vacuum (or run engine under conditions that change intake/EGR pressure) and confirm signal changes smoothly without dropouts or sudden jumps.
- If signal is constant, intermittent, or absent, perform a continuity check from sensor connector to ECM connector for signal, supply, and ground. Check for shorts to battery, ground or other circuits.
- Perform a wiggle test on harness/connectors while watching live data to try to reproduce the fault. Repair any damaged wiring or poor connector terminals.
- If wiring and connectors are good, replace the delta pressure sensor with a known-good unit and clear codes. Re-test for recurrence.
- If fault persists after sensor replacement, inspect related intake/EGR passages for blockages or restrictions that could force out-of-range differential readings.
- If wiring, sensor and passages check good, consider ECM input circuit testing or replacement per manufacturer guidance (rare).
- After repairs, erase codes and verify repairs with a road test and freeze-frame/live-data monitoring under the original fault conditions.
Likely causes
- Loose or corroded electrical connector at the delta pressure sensor
- Open or short in harness between sensor and ECM
- Failed sensor element
- External pressure/vacuum hose disconnected or degraded
- Connector terminal pushed out or contaminated
Fault status
Status
Upstream differential (delta) pressure sensor circuit disconnected or producing an implausible signal; ECM detected open/short or out-of-range reading and stored P1405.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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