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Home / DTC / C1339 — Left Rear LFI Pulse Fail Detect | Left Rear Low Frequency Initiator Fail Pulse Detected | Right Rear Low Frequency Initiator Fail Pulse Detected

C1339 — Left Rear LFI Pulse Fail Detect | Left Rear Low Frequency Initiator Fail Pulse Detected | Right Rear Low Frequency Initiator Fail Pulse Detected

Detailed page for trouble code C1339.

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Code

C1339

HYUNDAI C — Chassis

Left Rear LFI Pulse Fail Detect | Left Rear Low Frequency Initiator Fail Pulse Detected | Right Rear Low Frequency Initiator Fail Pulse Detected

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

Causes

  • Open, short, or intermittent wiring between left-rear LFI (wheel speed sensor) and ABS module
  • Poor or corroded connector at sensor or ABS module
  • Failed wheel speed/LFI sensor
  • Damaged or missing tone ring (reluctor) or foreign material blocking the sensor
  • Wheel hub or bearing excessive play causing incorrect signal
  • Fault in ABS/ESC control module or its ground/power supply

Symptoms

  • ABS and/or ESC/TRAC warning lamp illuminated
  • Traction control or stability control disabled
  • Possible ABS inoperative or reduced braking assist in some events
  • Cruise control or speed-related features may be disabled
  • Stored C1339 fault in ABS/ESC control module

What to check

  • Scan ECU and record freeze frame, related ABS/traction codes and live data
  • Visually inspect left-rear wheel speed sensor, tone ring, connector and wiring for damage or contamination
  • Wiggle-test wiring and connector while observing live wheel speed/LFI data for intermittent changes
  • Check connector pin condition for corrosion, bent pins or water intrusion
  • Verify power, ground and reference signals at the sensor (using manufacturer-specified voltages)
  • Measure sensor resistance and, if passive, check AC output while spinning wheel

Signal parameters

  • Behavior: wheel-speed pulse frequency proportional to wheel speed; amplitude and form depend on sensor type (passive magnetic = AC sine; active = digital/square or biased signal)
  • Active sensor: typically has a reference voltage (often ~5 V) and a signal waveform; check manufacturer spec for exact values
  • Passive sensor: produces AC voltage that increases with wheel speed; low or no AC at rest is normal
  • Resistance: varies by model — consult factory data. If resistance is open/short or far outside spec, replace sensor
  • Continuity to ABS module: low resistance expected; no open circuit between sensor connector and module pin

Diagnostic algorithm

  1. Read and record all ABS/ESC codes and freeze frame data. Note if multiple wheel sensor codes are present.
  2. Visually inspect left-rear sensor, tone ring, wheel hub and wiring harness. Repair obvious damage or contamination.
  3. With ignition ON (engine off), probe the sensor connector. For active sensors verify reference voltage and ground; for passive sensors check resistance across sensor leads and compare to spec.
  4. With vehicle raised and wheel free, spin the left-rear wheel and monitor live wheel speed sensor output with a scan tool or oscilloscope. Look for consistent pulses and increasing frequency with speed.
  5. Wiggle the wiring and connector while monitoring signal to reveal intermittent faults.
  6. If no or erratic signal, check continuity from sensor connector to ABS module pin and check for shorts to ground/power.
  7. Inspect tone ring for damaged or missing teeth and remove debris or corrosion. Repair or replace as required.
  8. Replace sensor or repair wiring/connector if tests indicate component fault. Reconnect and clear codes.
  9. Test drive and verify that left-rear wheel speed data is present and stable and that C1339 does not return. If it returns, consider ABS module input diagnostics or module replacement per factory procedure.

Likely causes

  • Corroded or disconnected sensor connector
  • Broken or chafed wiring harness near wheel or suspension
  • Failed left-rear wheel speed (LFI) sensor
  • Damaged or contaminated tone ring on the left-rear hub
  • Intermittent connection at ABS module

Fault status

⚠️ Status
Left Rear LFI pulse fail detected — left-rear wheel speed signal missing or invalid; ABS/ESC functionality may be reduced.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

C1330 C1335 C1340 C1350 U0121
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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