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Home / DTC / C181A00 — CAN Time-Out AAF

C181A00 — CAN Time-Out AAF

Detailed page for trouble code C181A00.

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Code

C181A00

HYUNDAI C — Chassis

CAN Time-Out AAF

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

Causes

  • Open or short in CAN High or CAN Low wiring to the AAF module
  • Poor connector pin contact, corrosion or bent pins at AAF/module or gateway connectors
  • Module power or ground fault to the AAF module
  • Faulty AAF module (internal failure)
  • Missing or incorrect CAN termination or damaged termination resistor(s)
  • Intermittent wiring fault (chafing, broken strand) or connector moisture

Symptoms

  • Associated system (AAF) inoperative or behaves intermittently
  • Related dashboard warning lamp(s) or MIL illuminated
  • Stored communication DTCs and possibly other network-related codes
  • Loss of data from the AAF module in live-data/scan tool
  • Intermittent operation of systems that rely on AAF messages

What to check

  • Retrieve all stored DTCs and freeze-frame data with a capable scan tool; note accompanying network codes
  • Verify vehicle battery voltage and charging system health (engine running and off), check fuses and power feeds to AAF
  • Confirm presence of the AAF module in the scan tool network list; observe live data and message counters if available
  • Visually inspect connectors and wiring to the AAF module, gateway, and related junctions for corrosion, damage or loose pins
  • Measure CAN bus physical layer with a multimeter and/or oscilloscope at and near the AAF connector
  • Check termination resistance across CANH and CANL (approx. 60 Ω for the whole bus)

Signal parameters

  • Recessive idle: CANH ≈ 2.5 V, CANL ≈ 2.5 V (both near midpoint)
  • Dominant state: CANH ≈ 3.5 V, CANL ≈ 1.5 V (differential ≈ 2 V)
  • Differential voltages: ~0 V (no activity) to ~2 V during dominant bits
  • Typical bus termination: two 120 Ω resistors in parallel = ~60 Ω across CANH–CANL
  • Common bus speeds: 500 kbps (powertrain) or 250 kbps/125 kbps on other networks — verify vehicle-specific speed

Diagnostic algorithm

  1. Connect diagnostic scanner, read and record C181A00 plus all other stored codes and freeze-frame data. Note whether the AAF module is present/responding on the bus.
  2. Check battery voltage (key on/off, engine running). Confirm power and ground at the AAF module connector and relevant fuses/relays.
  3. Visually inspect harness and connectors at the AAF module, gateway and splice points for damage, corrosion or loose pins. Repair as needed.
  4. With ignition on, measure CANH and CANL at the AAF connector: compare to expected idle voltages and observe for noise or stuck dominant state.
  5. Check termination resistance across CANH–CANL at multiple points; confirm ~60 Ω across the full bus. If open or wrong value, inspect termination resistors and wiring to them.
  6. Use an oscilloscope (preferred) or high-speed CAN tester to view message waveform and identify missing frames, collisions or noise. Check for the presence of AAF messages and message frequency.
  7. Perform wiggle tests on the wiring and connectors while monitoring network traffic to locate intermittent faults.
  8. If wiring and termination are good and the AAF does not transmit, try reseating the connector and rechecking. If possible, swap or bench-test the AAF module or connect a known-good module per manufacturer procedure.
  9. If module replacement is necessary, reprogram/configure per Hyundai requirements. Clear codes and retest drive cycle to confirm fault does not return.

Likely causes

  • Damaged or loose CAN connector at the AAF module
  • Broken/shorted CANH or CANL between the AAF and gateway/ECU
  • Failed AAF module electronics
  • Bad ground or supply to the AAF module causing it not to transmit
  • Open or incorrect termination on the CAN bus

Fault status

⚠️ Status
C181A00 — CAN Time-Out AAF: the vehicle’s CAN network did not receive expected messages from the AAF module within the configured timeout period. Indicates a communication loss between the AAF module and the CAN bus; requires investigation of wiring, power/ground, termination, and module health.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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371

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