P0599 on Chevrolet
Thermostat Heater Control Circuit High
P0599 on Chevrolet vehicles indicates thermostat heater control circuit high. Au7o has documented this code across 2 Chevrolet models — most commonly on Camaro, Cruze. This code relates to the engine cooling system's thermostat heater control circuit, used on engines with an electrically heated (map-controlled) thermostat that the computer can open early to fine-tune coolant temperature. The 'high' designation means the computer detected the control circuit voltage was higher than expected, indicating an electrical fault such as a short to voltage or an open circuit. It is generally an electrical/wiring problem rather than a mechanical cooling failure. It can affect how precisely the engine manages its operating temperature and fuel economy. Typical repair costs on Chevrolet range from $150 to $1,800, depending on the specific model and root cause.
Common Causes of P0599
- •Faulty electronically heated thermostat element/heater
- •Short to voltage in the heater control circuit
- •Open or damaged wiring/connector
- •Corroded or loose connector at the thermostat
- •Poor electrical ground
- •Faulty PCM/ECM driver (less common)
P0599 on Chevrolet by Model
Chevrolet Camaro(1 issue)
- Cooling System Problems and Engine Overheating2016-2023
Camaro owners report persistent overheating issues, particularly at idle, caused by cooling fan failures, faulty fan relays, clogged radiators, failing water pumps, and thermostat problems. Temperatures reaching 240-250°F have been reported.
Chevrolet Cruze(1 issue)
- 1.4T Coolant Leak at Water Outlet and Thermostat Housing2011-2016
The 2011-2016 Cruze 1.4L turbo engine has chronic coolant leaks from the water outlet housing and thermostat housing. These plastic components crack from heat cycling. The turbo coolant feed and return lines also develop leaks at the crimped rubber-to-metal connections. Some owners report replacing the water outlet multiple times.
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View P0599 across all makes →Frequently Asked Questions
What does P0599 mean on Chevrolet?▼
P0599 stands for "Thermostat Heater Control Circuit High." This code relates to the engine cooling system's thermostat heater control circuit, used on engines with an electrically heated (map-controlled) thermostat that the computer can open early to fine-tune coolant temperature. The 'high' designation means the computer detected the control circuit voltage was higher than expected, indicating an electrical fault such as a short to voltage or an open circuit. It is generally an electrical/wiring problem rather than a mechanical cooling failure. It can affect how precisely the engine manages its operating temperature and fuel economy. On Chevrolet specifically, this code is documented across 2 models.
What causes P0599 on Chevrolet vehicles?▼
Common causes on Chevrolet: Faulty electronically heated thermostat element/heater, Short to voltage in the heater control circuit, Open or damaged wiring/connector, Corroded or loose connector at the thermostat, Poor electrical ground. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0599 on a Chevrolet?▼
Repair costs on Chevrolet range from $150 to $1,800, depending on the specific model and root cause.
Which Chevrolet models have P0599 documented?▼
Au7o has documented P0599 on 2 Chevrolet models: Camaro, Cruze.