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Home / DTC / C2231 — Vacuum Pump System Fail

C2231 — Vacuum Pump System Fail

Detailed page for trouble code C2231.

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Code

C2231

HYUNDAI C — Chassis

Vacuum Pump System Fail

Brand: HYUNDAI
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Failed vacuum pump motor
  • Open/short in vacuum pump power or control wiring
  • Blown fuse or bad relay for the pump circuit
  • Leaking vacuum lines, hoses, or fittings
  • Faulty one-way check valve or vacuum reservoir
  • Faulty vacuum sensor or pressure transducer

Symptoms

  • Brake pedal feels hard or requires more effort (reduced brake assist)
  • Brake warning light or ABS/ESC warning lamp illuminated
  • DTC C2231 stored in ABS/vehicle control module
  • Audible abnormal noise from vacuum pump (grinding or whining)
  • Poor engine idle or increased engine load in rare cases if pump draws excessive current

What to check

  • Read DTCs and freeze-frame data with a capable scan tool; note MIL/warning lamp status
  • Check for additional stored codes in ABS, engine or BCM that may be related
  • Visually inspect vacuum pump, vacuum lines, check valve and reservoir for damage or disconnected hoses
  • Inspect pump electrical connector, wiring harness for corrosion, loose pins, or damage
  • Verify fuses and relays for the vacuum pump circuit
  • Measure supply voltage at the pump connector with key on/engine off and while commanded

Signal parameters

  • Supply voltage to pump: ~11–14 V (key on/engine running)
  • Pump current draw: manufacturer-specific; typically 1–10 A peak (measure with ammeter)
  • Vacuum reservoir pressure: expected vacuum at idle or when commanded (example: > -60 kPa or vacuum reading per service manual)
  • Vacuum sensor reading: matches actual vacuum within sensor tolerance
  • Control signal (if PWM): duty cycle or frequency from ABS/ECU when commanding pump

Diagnostic algorithm

  1. Verify DTC and any related codes with a scan tool; record freeze frame and live data.
  2. Perform a visual inspection: vacuum hoses, check valve, reservoir, pump mounting and electrical connectors.
  3. Check fuses/relays for the vacuum pump circuit; replace if faulty and retest.
  4. With ignition on, measure voltage at pump connector. If no voltage, trace wiring back to relay/fuse/module and repair open circuit.
  5. Command the pump ON using a capable scan tool (if supported) and confirm pump runs audibly and by measuring voltage/current at the pump.
  6. If pump runs but vacuum is low, inspect hoses, check valve and reservoir for leaks; pressure test or use a hand vacuum pump to isolate leak.
  7. If vacuum is not produced and pump has proper supply but minimal/no current draw, remove pump and bench-test by applying direct battery voltage briefly (observe safety and torqueing recommendations). If pump does not run or draws excessive current, replace pump.
  8. If pump bench-tests OK, inspect wiring for high resistance, intermittent opens, or poor ground; repair as needed.
  9. Verify vacuum sensor operation by comparing sensor output to measured vacuum with a gauge; replace sensor if out of spec.
  10. After repairs, clear codes, perform functional tests and a road test to ensure the vacuum system builds and maintains required vacuum and no codes return. If codes persist, consider control module diagnostics per manufacturer's procedures.

Likely causes

  • Vacuum pump not running due to blown fuse, relay, or open wiring
  • Pump runs but does not produce vacuum because of internal failure
  • Vacuum hose or check valve leak preventing reservoir from building vacuum
  • Bad vacuum sensor sending incorrect feedback to control module
  • Intermittent connector or ground causing sporadic pump operation

Fault status

⚠️ Status
Vacuum pump system failure detected — pump performance, circuit or vacuum integrity is out of expected range; reduced brake assist or warning lamp may occur.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

C2230 C2221 C2381 C2232
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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