P0116 on Chevrolet: How to Diagnose & Fix
Engine Coolant Temperature Sensor 1 Circuit Range/Performance
2 Chevrolet models · 2 documented issues · 1 critical · $150-$600 repair
P0116 on Chevrolet by model: symptoms, diagnosis and fix
On the 2.2L/2.4L Ecotec the thermostat is integrated into a plastic housing on the back side of the engine facing the firewall, and the water pump sits behind the timing cover on the passenger side. Both are recurring leak points. The rear thermostat housing seal hardens and the housing itself corrodes and seeps, and because the leak is tucked against the firewall the coolant evaporates on the hot block instead of dripping — so owners chase a steadily dropping reservoir with no puddle in the driveway, a complaint that appears over and over on the Cobalt forums. The water pump leaks at its gasket toward the passenger side, and because it is timing-chain driven, a leaking pump can wash the front of the engine and contaminate the chain area. A slow leak that runs the car low leads to overheating and, on the Ecotec, a warped or cracked head.
Common Symptoms
- Coolant reservoir slowly drops with no visible puddle
- Sweet coolant smell after driving
- White crust or dried residue at the back of the engine near the firewall
- Temperature gauge climbing or heater blowing cold
- Overheat warning in traffic
How to Fix
Pressure-test the cooling system cold at about 15 psi and inspect the back of the engine with a light and mirror while it holds pressure — that is where the thermostat housing lives and where the leak hides. Replace the thermostat housing as an assembly with a new seal rather than reusing a corroded housing. If the leak is on the passenger side near the timing cover, the water pump and its gasket are the likely source; replace the pump with an OE-quality unit and refill with the correct Dex-Cool. After repair, burp the system properly — the Ecotec traps air and an unbled system overheats and mimics the original fault. If you find oil in the coolant reservoir, stop and test for head gasket failure before spending money on the pump.
Sources for this issue (3)
GM issued urgent dealer message DCS6982 on August 14, 2024 covering 2024 vehicles with the 1.2L gasoline engine - Chevrolet Trax and Trailblazer, Buick Encore GX and Envista. The engine control module may fail to properly control ignition timing following certain Auto Engine Stop/Start restart events. When that happens the malfunction indicator lamp comes on and the engine runs rough or audibly knocks; GM's own bulletin warns that continuing to drive with the knock present can cause engine damage. The matching service bulletin, 24-NA-064, directs technicians to reprogram the ECM when the MIL is set with DTC P0324 (knock control system error) and/or P0116 (engine coolant temperature sensor performance). Because detonation on a small-displacement turbo three is exactly the loading that hurts rod bearings, this is worth chasing promptly rather than living with.
Common Symptoms
- Check engine light after an Auto Stop/Start restart
- Audible engine knock or detonation rattle
- Rough running after the engine auto-restarts
- Hesitation pulling away from a stop
How to Fix
Free remedy - the dealer reprograms the Engine Control Module with updated calibration; no parts are required. Reference GM message DCS6982 and bulletin 24-NA-064 when booking. If the knock persists after the reflash, insist on a borescope and an oil-analysis/bearing inspection rather than accepting 'normal three-cylinder noise'. In the interim you can reduce exposure by switching Auto Stop/Start off at each start and running top-tier 87-octane or better fuel.
Sources for this issue (2)
P0116 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0116 mean on a Chevrolet?
P0116 stands for "Engine Coolant Temperature Sensor 1 Circuit Range/Performance." P0116 means the engine control module detected an engine coolant temperature (ECT) sensor reading that is within wiring limits but doesn't make sense — for example, it doesn't rise as the engine warms up, or it disagrees with other temperature data. The ECT sensor reports coolant temperature, which the computer uses for fuel mixture, ignition timing, cooling-fan control, and emissions monitors. An implausible reading can cause poor fuel economy, hard cold starts, or failed emissions readiness. It is generally drivable but should be fixed for proper engine management. On Chevrolet it is documented across 2 models: Cobalt, Trax.
What are the most common causes of P0116?
The most common causes of P0116 are: Faulty or drifting engine coolant temperature sensor, Stuck-open thermostat (engine never reaches normal temp), Low coolant level or air in the cooling system, Wiring or connector resistance affecting the signal, Sensor reading inconsistent with intake-air temperature at cold start, Corroded sensor connector, PCM fault (less common). The specific cause varies by vehicle.
How much does it cost to fix P0116 on a Chevrolet?
Published repair estimates on Chevrolet range from $150 to $600 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0116 on a different make?
View P0116 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.