C1A40

Code

LAND ROVER C — Chassis

Power supply voltage of the sensor

Brand: LAND ROVER

Type: C — Chassis

Views: UK: 16 EN: 37 RU: 18

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Page language: EN

Causes

Blown fuse or fusible link for sensor/ECU supply
Damaged or corroded connector at the sensor or ECU
Broken, shorted or high-resistance power or ground wire
Poor chassis ground at sensor or ECU
Faulty sensor (internal supply/regulator failure)
Faulty ECU/power module or internal connector

Symptoms

Malfunction Indicator Lamp (MIL) or dash fault warning illuminated
Related system or function degraded or inoperative (depending on the sensor)
Stored fault code and freeze frame data available
Intermittent faults that may appear after driving or in wet conditions
Vehicle may go into limp or reduced functionality mode if the sensor feeds a critical system

What to check

Read and record all related fault codes and freeze frame data with a capable scan tool
Inspect fuses and fusible links for the affected module/circuit
Visually inspect sensor connector for corrosion, bent pins, contamination and secure mating
Visually route and inspect wiring for chafing, damage, stretches or repairs
Back-probe sensor supply and ground with ignition ON and compare to expected values
Check for intermittent faults by wiggling the harness and connectors while monitoring live data or voltage

Signal parameters

Expected sensor supply voltage: typically 5.0 V reference or switched 12 V depending on sensor type (verify against wiring diagram)
Good chassis/ECU ground: near 0.0–0.2 V when measured between ground terminal and chassis
Voltage at sensor with ignition ON (no cranking): battery voltage for switched supplies (~11.5–14.5 V) or ~5.0 V for reference rails
Open-circuit wiring: very low or 0 V on expected supply
Short to battery: supply at battery voltage when it should be lower (rare)
Intermittent: fluctuating voltage or drop under load

Diagnostic algorithm

Connect a factory-level or capable diagnostic scanner and record C1A40 plus any related codes and freeze frame data.
Obtain the wiring diagram and identify the sensor, its supply pin, reference pin and ground pin at both sensor and ECU.
Visually inspect sensor connector and associated harness for obvious damage, corrosion or contamination; repair or replace connector as necessary.
Check fuses and fusible links for the sensor/ECU supply circuit; replace any blown fuses and retest.
Back-probe the sensor supply pin with a digital multimeter (DMM) with ignition ON (engine off); verify expected voltage (see wiring diagram).
Measure resistance/continuity from sensor ground pin to battery negative/chassis; expect very low resistance (
If supply is missing or low, trace wiring toward ECU: check continuity to the fuse and to the ECU pin. Repair any opens or high-resistance sections.
If supply is present at the fuse but lost at the sensor, inspect/repair harness between them. If supply is lost at the ECU pin, suspect ECU/power module or internal connector issue—confirm with wiring checks before replacement.
If supply and ground are correct, monitor sensor output while operating the system; if output is absent or implausible, consider replacing the sensor.
After repairs, clear codes and perform functional test/road test to verify the fault does not return. If intermittent, perform extended drive cycle testing.
If all wiring and sensor check good and fault persists, consult manufacturer service info for ECU test/replacement procedures or software updates.

Likely causes

blown or corroded supply fuse
open or high-resistance supply wire to sensor
bad ground at sensor or ECU
corroded sensor connector pins
failed sensor internal regulator

Fault status

⚠️ Status

Control module detected an out-of-range or missing power supply voltage on the sensor circuit; diagnostic trouble code C1A40 stored.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-1.5 hours

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C1A40 — Power supply voltage of the sensor