Cause
Faulty engine coolant temperature sensor
The sensor the module uses to decide how much extra fuel a cold engine needs. A sensor reading colder than reality makes the engine over-fuel indefinitely — poor economy, sooty plugs, and a catalyst working far harder than it should.
The temperature gauge may look entirely normal throughout, because on many vehicles it is driven from a separate signal.
Typically an easy fix. Often worth checking before paying anyone to look.
Some of these codes mean you should stop driving
1 of the 36 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (36)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0115 Engine Coolant Temperature Sensor 1 Circuit Likely for this code High
- P0116 Engine Coolant Temperature Sensor 1 Circuit Range/Performance Likely for this code Moderate
- P0117 Engine Coolant Temperature Sensor 1 Circuit Low Likely for this code High
- P0118 Engine Coolant Temperature Sensor 1 Circuit High Likely for this code High
- P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control Likely for this code Moderate
- P0126 Insufficient Coolant Temperature for Stable Operation Likely for this code Moderate
- P0C42 Hybrid/EV Battery Pack Coolant Temperature Sensor A Circuit Likely for this code High
- P0C43 Hybrid/EV Battery Pack Coolant Temperature Sensor A Circuit Range/Performance Likely for this code High
- P0C44 Hybrid/EV Battery Pack Coolant Temperature Sensor A Circuit Low Likely for this code High
- P0C45 Hybrid/EV Battery Pack Coolant Temperature Sensor A Circuit High Likely for this code High
- P0C46 Hybrid/EV Battery Pack Coolant Temperature Sensor A Circuit Intermittent/Erratic Likely for this code High
- P0CD5 Hybrid/EV Battery Pack Coolant Temperature Sensor B Circuit Likely for this code High
- P0CD6 Hybrid/EV Battery Pack Coolant Temperature Sensor B Circuit Range/Performance Likely for this code High
- P0CD7 Hybrid/EV Battery Pack Coolant Temperature Sensor B Circuit Low Likely for this code High
- P0CD8 Hybrid/EV Battery Pack Coolant Temperature Sensor B Circuit High Likely for this code High
- P0CD9 Hybrid/EV Battery Pack Coolant Temperature Sensor B Circuit Intermittent/Erratic Likely for this code High
- P2182 Engine Coolant Temperature Sensor 2 Circuit Likely for this code Moderate
- P2183 Engine Coolant Temperature Sensor 2 Circuit Range/Performance Likely for this code Moderate
- P2184 Engine Coolant Temperature Sensor 2 Circuit Low Likely for this code Moderate
- P2185 Engine Coolant Temperature Sensor 2 Circuit High Likely for this code Moderate
- P26A3 Engine Coolant Bypass Valve A Range/Performance Likely for this code Moderate
- P0119 Engine Coolant Temperature Sensor 1 Circuit Intermittent/Erratic Moderate
- P0128 Coolant Thermostat — Temperature Below Regulating Point Moderate
- P0172 System Too Rich — Bank 1 High
- P0175 System Too Rich — Bank 2 High
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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