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Home / DTC / C1505 — Low Pressure Switch

C1505 — Low Pressure Switch

Detailed page for trouble code C1505.

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Code

C1505

HYUNDAI C — Chassis

Low Pressure Switch

Brand: HYUNDAI
Type: C — Chassis
AI status
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Page language: EN

Causes

  • Low refrigerant/hydraulic/fuel pressure in the monitored system (depending on application)
  • Failed/shorted/open low pressure switch
  • Corroded, loose or damaged connector at the switch
  • Broken, chaffed or shorted wiring between switch and control module
  • Blown fuse or faulty relay in the associated circuit
  • Intermittent grounding or poor pin contact at control module

Symptoms

  • Malfunction indicator lamp or ABS/traction/A/C system warning lamp illuminated (system dependent)
  • A/C compressor may not engage (if A/C low-pressure cutoff)
  • Loss of system function controlled by the pressure input (e.g., no compressor clutch, limp mode for systems that use pressure feedback)
  • Intermittent system operation or systems that only work after restart
  • Possible unusual system behavior (reduced cooling, poor fuel system performance, etc., depending on application)

What to check

  • Retrieve DTC with OEM-capable scan tool and record freeze-frame data and related codes
  • Inspect service manual for the specific system the switch monitors (A/C, fuel, hydraulic) and for the switch pinout and expected signal type
  • Visually inspect the switch, connector and wiring for corrosion, loose pins, damaged insulation, or evidence of fluid intrusion
  • Check fuse(s) and relay(s) for the circuit powering the switch
  • Backprobe the switch connector and check for reference voltage, ground and signal at key operating conditions
  • Measure switch continuity/ohms across terminals while applying known pressure (or using a hand pump/gauge where safe and applicable)

Signal parameters

  • Switch output: typically open or closed contact (binary) — closed when pressure above threshold, open when below (or vice versa depending on design)
  • Expected reference voltage: often 0 V (ground) or battery/ignition feed (12 V) depending on switched side; consult OEM manual
  • Expected continuity: near 0 ohms when closed, open/infinite when open (use ohmmeter)
  • Typical pressure trip point: varies by system (A/C low-pressure cutoff commonly around 25–50 psi low side; consult spec)
  • Signal behavior: should change state promptly when pressure crosses factory-specified threshold

Diagnostic algorithm

  1. Connect a scan tool, confirm C1505 and note related/preceding codes and freeze-frame data. Verify ignition state and system conditions when the code set.
  2. Review the factory wiring diagram for the low pressure switch circuit: identify power, ground and signal path to control module.
  3. Perform visual inspection of switch, connector and wiring for damage, corrosion, loose pins, or evidence of leaks.
  4. With ignition on (engine off) backprobe connector: verify referenced power/ground present per wiring diagram. If no power/ground, repair fuse/relay/wiring.
  5. Check switch operation: measure continuity across switch while varying system pressure (use appropriate gauges or service equipment). Compare behavior to OEM trip thresholds.
  6. Measure signal voltage to the module with the system in different pressure states (low and normal). Confirm the control module sees state change when pressure threshold is crossed.
  7. If wiring/power/ground are good but switch does not change state correctly, remove and bench-test or replace the low pressure switch.
  8. If switch and wiring test good but code persists, inspect/repair grounds and connector pins at the control module. If wiring harness repairs are done, recheck for intermittent faults.
  9. After repairs, clear codes, restore system charge if applicable (A/C), then perform functional test and road/test to confirm code does not return.
  10. If all tests point to control module fault, consult advanced diagnostics or dealer service — do not replace module without verifying wiring and sensor operation.

Likely causes

  • Low refrigerant charge in A/C system causing switch to open
  • Failed pressure-switch internal contact (stuck open/closed)
  • Wiring harness chafe or water ingress at connector
  • Connector pin corrosion or poor mating
  • Blown fuse feeding the pressure switch circuit

Fault status

⚠️ Status
C1505 — Low Pressure Switch: Circuit or pressure out of range detected. Inspect switch, wiring, connectors, fuses and actual system pressure.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

C1500 C1501 P0191 P0193 P0522 P0455
371

Browse 371 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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