Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / C2123 — Servo Pump Relay Elec.

C2123 — Servo Pump Relay Elec.

Detailed page for trouble code C2123.

34,405codes
59brands
11,914generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

C2123

HYUNDAI C — Chassis

Servo Pump Relay Elec.

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

Causes

  • Faulty servo pump relay (coil or contacts)
  • Blown fuse supplying relay or pump
  • Open or shorted wiring between relay, pump and control module
  • Corroded/loose relay socket or connector pins
  • Failed servo/pump motor drawing abnormal current
  • Poor chassis or battery ground

Symptoms

  • ABS and/or ESC warning lamp illuminated
  • Loss of active pump-assisted functions (reduced ABS/ESC performance)
  • Brake pedal may feel firmer/unchanging when ABS should activate
  • Pump not audible when ABS/ESC activates
  • Intermittent operation of ABS/ESC
  • Possible stored related DTCs for pump, relay, or low voltage

What to check

  • Read and record all stored codes and freeze frame with a capable scan tool
  • Check battery voltage (engine off and cranking) and battery condition
  • Inspect fuses for pump/ABS/ESC circuit and replace if blown
  • Visually inspect relay, relay socket and connectors for corrosion, damage or loose pins
  • Backprobe relay coil/control terminal to confirm control signal when ABS is commanded
  • Measure supply voltage and ground at pump and relay harness

Signal parameters

  • Relay control voltage: ~0 V (inactive) and approx battery voltage (11–14.5 V) when commanded
  • Relay coil resistance (typical automotive relay): roughly 50–150 ohms (verify service spec)
  • Supply feed at relay: battery voltage within 11–15 V with key on
  • Ground: near 0 V; low-resistance connection to chassis
  • Pump motor current draw when running: typically several amps (commonly 5–20 A depending on vehicle); large deviations indicate pump fault
  • No excessive voltage drop (

Diagnostic algorithm

  1. Retrieve all ABS/ESC and related codes and note freeze-frame data. Clear codes and attempt to re-produce.
  2. Verify battery state-of-charge and charging system. Low battery can produce false electrical faults.
  3. Visually inspect relay, fuse and wiring for obvious damage, corrosion or fluid intrusion. Replace corroded connectors.
  4. Check/replace fuse for pump/relay if blown. If fuse blows again, suspect short to power/ground or pump fault.
  5. With ignition ON, backprobe relay coil/control terminal. Command ABS pump ON with scan tool and confirm control voltage appears at coil terminal.
  6. Measure supply voltage at relay power terminal and at pump connector while commanding pump; note any significant voltage drop.
  7. Measure relay coil resistance (relay removed) and compare to specification; bench-test relay operation if uncertain.
  8. Command pump while monitoring current draw with an appropriate meter/clamp. Abnormally high current suggests pump motor fault; no current suggests open circuit/relay fault.
  9. Check continuity and resistance of wiring between relay, pump and ABS module; repair any opens or high resistance grounds.
  10. If wiring, relay and pump check good, consider replacing relay and re-test. If fault persists, consider ABS/ESC control module diagnosis/repair by qualified technician.
  11. After repairs, clear codes, verify pump operation via scan tool and perform functional/road test to confirm fault is resolved.

Likely causes

  • Defective relay or relay socket corrosion
  • Open/short in supply or ground conductor to relay/pump
  • Blown fuse protecting pump/relay circuit
  • Pump motor internal failure/high current
  • Intermittent connector (moisture/corrosion)
  • Faulty ABS/ESC module (less common)

Fault status

⚠️ Status
Electrical fault detected in servo pump relay circuit — relay open/short or supply/ground problem. ABS/ESC pump may not run; warning lamp illuminated.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5 - 3.0 hours

Similar codes

C1251 C1256 C2120 C2140 C1221
371

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

HYUNDAI

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .