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Home / DTC / U0116 — Lost Communication With Coolant Temperature Control Module

U0116 — Lost Communication With Coolant Temperature Control Module

Detailed page for trouble code U0116.

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U0116

Generic U — Network/User

Lost Communication With Coolant Temperature Control Module

Brand: Generic
Type: U — Network/User
Views: UK: 14 EN: 17 RU: 15
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted CAN/LIN communication wiring
  • Faulty coolant temperature control module (internal failure)
  • Lost or intermittent power or ground to the module
  • Blown fuse or failed relay supplying the module
  • Poor connector contacts, corrosion or water intrusion
  • Failed or missing network termination resistor(s)

Symptoms

  • MIL (Malfunction Indicator Lamp) or warning message on dash
  • Coolant temperature gauge erratic, pegged, or unavailable
  • Fans, thermostat or coolant-related functions may not operate correctly
  • Reduced engine performance or limp mode in some vehicles
  • Other modules reporting related network communication codes
  • Stored U0116 in module memory; possible freeze frame data

What to check

  • Scan vehicle with a capable scan tool: confirm U0116, check for related U-codes and module presence
  • Verify battery voltage is within specification and perform a key cycle
  • Inspect fuses and relays for the coolant temperature control module circuit
  • Visually inspect connectors and wiring at the suspect module for damage, corrosion, or loose pins
  • Check module power and ground pins for proper voltage and low resistance to chassis ground
  • Check CAN/LIN bus voltages at the module connector (CANH/CANL idle voltages and differential)

Signal parameters

  • CAN bus idle/recessive: CAN High ~2.5–3.5 V, CAN Low ~1.5–2.5 V (both about 2.5 V if measured relative to ground)
  • CAN differential voltage: ~0 V (recessive) and up to ~2 V (dominant) during traffic
  • At normal operation: observe regular CAN frames on a scan tool or CAN scope; absence indicates lost comms
  • Module power supply: battery voltage (~11–14.5 V with engine running) at module Vbatt pin
  • Ground: near 0 Ω continuity to chassis ground (

Diagnostic algorithm

  1. Use a scan tool to verify U0116 and note any related U-codes or live data. Check whether the coolant temperature control module is listed/communicating.
  2. Record freeze frame or snapshot data and perform a key cycle to see if code is persistent.
  3. Visually inspect the module connector, wiring harness, and nearby components for damage, corrosion, or signs of water intrusion.
  4. Check fuses and relays that supply the coolant temperature control module; replace any blown fuses and retest.
  5. With ignition on, verify module supply voltage and ground at the connector pins. Repair any open/poor power or ground connections.
  6. Measure CANH and CANL voltages at the module connector while key is on and engine off. Compare to expected signal parameters.
  7. Use a CAN bus meter or oscilloscope to check for valid CAN frames, bus errors, or a stuck dominant state. Isolate by disconnecting nodes (one at a time) to find a faulted device.
  8. If wiring and bus look correct, try communication with the module from the scan tool. If still not present, consider reprogramming or replacing the module per manufacturer procedures.
  9. After repairs, clear codes and perform a functional test and road test to confirm the fault does not return.
  10. If intermittent, perform extended drive cycles and monitor bus traffic or install a data logger to capture the failure when it occurs.

Likely causes

  • Corroded/loose connector at the coolant temperature control module
  • Blown fuse or bad module power/ground circuit
  • CAN high/low short or open in wiring harness near module
  • Module internal failure or ECU fault
  • Faulty network termination or shorted node on the CAN bus

Fault status

⚠️ Status
Lost communication with Coolant Temperature Control Module — module not responding on vehicle communication bus. Code stored when module cannot be reached.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5 - 3.0 hours

Similar codes

U0100 U0101 U0115 U0121 U0140
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Code

U0116

HYUNDAI U — Network/User

Lost Communication With Coolant Temperature Control Module

Brand: HYUNDAI
Type: U — Network/User
Views: UK: 12 EN: 21 RU: 13
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted CAN/LIN communication wiring
  • Faulty coolant temperature control module (internal failure)
  • Lost or intermittent power or ground to the module
  • Blown fuse or failed relay supplying the module
  • Poor connector contacts, corrosion or water intrusion
  • Failed or missing network termination resistor(s)

Symptoms

  • MIL (Malfunction Indicator Lamp) or warning message on dash
  • Coolant temperature gauge erratic, pegged, or unavailable
  • Fans, thermostat or coolant-related functions may not operate correctly
  • Reduced engine performance or limp mode in some vehicles
  • Other modules reporting related network communication codes
  • Stored U0116 in module memory; possible freeze frame data

What to check

  • Scan vehicle with a capable scan tool: confirm U0116, check for related U-codes and module presence
  • Verify battery voltage is within specification and perform a key cycle
  • Inspect fuses and relays for the coolant temperature control module circuit
  • Visually inspect connectors and wiring at the suspect module for damage, corrosion, or loose pins
  • Check module power and ground pins for proper voltage and low resistance to chassis ground
  • Check CAN/LIN bus voltages at the module connector (CANH/CANL idle voltages and differential)

Signal parameters

  • CAN bus idle/recessive: CAN High ~2.5–3.5 V, CAN Low ~1.5–2.5 V (both about 2.5 V if measured relative to ground)
  • CAN differential voltage: ~0 V (recessive) and up to ~2 V (dominant) during traffic
  • At normal operation: observe regular CAN frames on a scan tool or CAN scope; absence indicates lost comms
  • Module power supply: battery voltage (~11–14.5 V with engine running) at module Vbatt pin
  • Ground: near 0 Ω continuity to chassis ground (

Diagnostic algorithm

  1. Use a scan tool to verify U0116 and note any related U-codes or live data. Check whether the coolant temperature control module is listed/communicating.
  2. Record freeze frame or snapshot data and perform a key cycle to see if code is persistent.
  3. Visually inspect the module connector, wiring harness, and nearby components for damage, corrosion, or signs of water intrusion.
  4. Check fuses and relays that supply the coolant temperature control module; replace any blown fuses and retest.
  5. With ignition on, verify module supply voltage and ground at the connector pins. Repair any open/poor power or ground connections.
  6. Measure CANH and CANL voltages at the module connector while key is on and engine off. Compare to expected signal parameters.
  7. Use a CAN bus meter or oscilloscope to check for valid CAN frames, bus errors, or a stuck dominant state. Isolate by disconnecting nodes (one at a time) to find a faulted device.
  8. If wiring and bus look correct, try communication with the module from the scan tool. If still not present, consider reprogramming or replacing the module per manufacturer procedures.
  9. After repairs, clear codes and perform a functional test and road test to confirm the fault does not return.
  10. If intermittent, perform extended drive cycles and monitor bus traffic or install a data logger to capture the failure when it occurs.

Likely causes

  • Corroded/loose connector at the coolant temperature control module
  • Blown fuse or bad module power/ground circuit
  • CAN high/low short or open in wiring harness near module
  • Module internal failure or ECU fault
  • Faulty network termination or shorted node on the CAN bus

Fault status

⚠️ Status
Lost communication with Coolant Temperature Control Module — module not responding on vehicle communication bus. Code stored when module cannot be reached.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5 - 3.0 hours

Similar codes

U0100 U0101 U0115 U0121 U0140
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