Fault code P1116 – a step-by-step guide to diagnosing and fixing it

Error code P1116 is displayed and the check engine light is on - what does this mean?

DTC P1116 is recognized by the OBD/EOBD system when a problem is detected with the coolant temperature sensor circuit outside the normal operating range. This manufacturer-specific fault code mainly affects the engine cooling system and temperature monitoring, although it can have slightly different meanings for different vehicle makes.

What causes can this fault code have?

• Defective coolant temperature sensor
• Damaged cable connections to the temperature sensor
• Corroded or loose plug connections
• Faulty engine control unit software
• Low coolant levels in the system
• Defective thermostat
• Short circuit in the sensor wiring
• Ground fault in the sensor system

What symptoms occur in parallel with error code P1116?

• Starting problems: The vehicle starts with difficulty or irregularly, especially when the engine is cold
• Irregular idling: The engine runs unstable or stutters at idle speed
• Increased fuel consumption: Significantly higher fuel consumption values than usual
• Poor engine performance: Reduced power and sluggish acceleration
• Radiator fan runs continuously: The fan switches on more frequently than normal
• Incorrect temperature display: Unrealistic values on the coolant temperature display

How can the problem with fault code P1116 be rectified?

• Repairing fault code P1116 requires a systematic approach to identify the exact cause.
• Replace the coolant temperature sensor: Remove the faulty sensor, clean the threads and install a new OEM sensor with proper torque
• Repair wiring harness: Check all wire connections to the sensor for damage, repair broken wires and properly insulate them
• Clean and secure plug connections: Disconnect the plug connections, clean them with contact spray and ensure a secure fit
• Fill and bleed the cooling system: Fill the cooling system with the correct coolant specification and bleed it completely
• Replace thermostat: Replace a faulty thermostat with a new one and check for proper operation
• Update engine control unit software: Perform a software update of the ECU or have it programmed by a specialist workshop