Code
C1997
LAND ROVER
C — Chassis
Pressure controller plausibility failure
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UK: 2
EN: 7
RU: 4
AI status
Completed
Completed
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Causes
- Faulty pressure sensor (out-of-range or intermittent)
- Faulty pressure controller/valve block or pump/compressor
- Wiring fault: open, short to ground, short to battery, or high resistance in signal/supply/ground
- Leaking pressure lines, fittings or actuators causing pressure not to reach expected value
- Low hydraulic/air fluid level or air ingress in hydraulic lines
- Corroded/poor connector connections at sensor, actuator or controller
Symptoms
- Malfunction indicator or specific system warning lamp illuminated
- Related system enters limp/reduced functionality mode (reduced steering assist, suspension stuck, brake assist restricted, etc.)
- Unusual pump/compressor noise or continuous pump running
- Vehicle sagging or incorrect ride height (if air suspension related)
- Intermittent system operation or repeated DTC set after clearing
What to check
- Read stored and pending DTCs and freeze frame data with a capable scan tool
- Check live data: pressure sensor reading, commanded pressure/valve position, pump/compressor duty cycle, system voltages
- Inspect wiring and connectors at pressure sensor, controller module, pump/compressor and valve block for damage, corrosion or water ingress
- Check fuses and relays for the pressure system and control modules
- Visually inspect pressure lines, hoses, fittings and actuators for leaks or physical damage
- Measure supply voltage and ground continuity at sensor and controller
Signal parameters
- Pressure sensor voltage: typically ~0.5–4.5 V (dependent on sensor design)
- Pressure sensor reading: expected system-specific range (e.g., 0–10 bar / 0–145 psi depending on system)
- Controller command: valve PWM duty cycle 0–100% or commanded pressure setpoint
- Pump/compressor current draw and duty cycle during commanded pressure build
- Supply voltage: nominal battery voltage ~11–14.5 V while key on
- CAN messages/comm status: module should be able to communicate on vehicle network
Diagnostic algorithm
- Read and record all stored/pending DTCs and freeze frame data. Note conditions when fault set.
- Clear codes and attempt to re-create fault by exercising the affected system or performing a test drive while monitoring live data.
- Compare commanded pressure/actuator commands with measured pressure sensor values in real time. Look for delays, no response, or out-of-range readings.
- Visually inspect connectors, pins and wiring harnesses at sensor, valve block/pump and control module. Wiggle-test while watching live data for intermittent changes.
- Measure sensor supply, ground and signal voltage at the sensor connector. Verify against expected ranges.
- Perform a leak-down or pressure-hold test on the pressure circuit if applicable to confirm system integrity.
- Command the pump/compressor and valves via diagnostic tool to verify operation and measure current draw (high draw may indicate mechanical binding; no draw may indicate electrical fault).
- If wiring and power are good but readings remain implausible, bench-test or replace the pressure sensor or valve block per manufacturer procedure.
- If component replacement performed, clear codes, perform any required module calibrations or adaptations, and road-test to confirm repair.
- If fault persists after component checks/replacements, consult OEM technical service information for module reprogramming, known faults or extended diagnostics.
Likely causes
- Faulty pressure sensor or connector corrosion
- Failed pump/compressor or pressure regulator/valve
- Broken or shorted wiring between sensor and control module
- Leak in pressure circuit preventing system from reaching commanded pressure
- ECU/module internal fault or mismatched software
Fault status
Status
Pressure controller plausibility failure — affected system may be restricted. Service recommended.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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