Code
U0116
Generic
U — Network/User
Lost Communication With Coolant Temperature Control Module
AI status
Completed
Completed
100%
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
- 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.
- Record freeze frame or snapshot data and perform a key cycle to see if code is persistent.
- Visually inspect the module connector, wiring harness, and nearby components for damage, corrosion, or signs of water intrusion.
- Check fuses and relays that supply the coolant temperature control module; replace any blown fuses and retest.
- With ignition on, verify module supply voltage and ground at the connector pins. Repair any open/poor power or ground connections.
- Measure CANH and CANL voltages at the module connector while key is on and engine off. Compare to expected signal parameters.
- 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.
- 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.
- After repairs, clear codes and perform a functional test and road test to confirm the fault does not return.
- 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
Repair manuals
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Code
U0116
HYUNDAI
U — Network/User
Lost Communication With Coolant Temperature Control Module
AI status
Completed
Completed
100%
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
- 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.
- Record freeze frame or snapshot data and perform a key cycle to see if code is persistent.
- Visually inspect the module connector, wiring harness, and nearby components for damage, corrosion, or signs of water intrusion.
- Check fuses and relays that supply the coolant temperature control module; replace any blown fuses and retest.
- With ignition on, verify module supply voltage and ground at the connector pins. Repair any open/poor power or ground connections.
- Measure CANH and CANL voltages at the module connector while key is on and engine off. Compare to expected signal parameters.
- 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.
- 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.
- After repairs, clear codes and perform a functional test and road test to confirm the fault does not return.
- 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
Repair manuals
Manual library for HYUNDAI
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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