P0599 on BMW
Thermostat Heater Control Circuit High
P0599 on BMW vehicles indicates thermostat heater control circuit high. Au7o has documented this code across 1 BMW model — most commonly on X1. 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 BMW range from $500 to $1,200, 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 BMW by Model
BMW X1(1 issue)
- Coolant Leaks - Water Pump & Thermostat - F48 X12016-2023
The F48 X1 commonly develops coolant leaks from the electric water pump and thermostat housing. The electric water pump (auxiliary pump) is a wear item that typically fails between 60,000-100,000 miles. The thermostat housing develops cracks or seal failures, causing coolant leaks. Symptoms include coolant loss, low coolant warnings, and visible leaks. The electric water pump is critical for preventing overheating when the engine is off or during cold starts. This is a common issue across many BMW models with B-series engines.
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What does P0599 mean on BMW?▼
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 BMW specifically, this code is documented across 1 model.
What causes P0599 on BMW vehicles?▼
Common causes on BMW: 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 BMW?▼
Repair costs on BMW range from $500 to $1,200, depending on the specific model and root cause.
Which BMW models have P0599 documented?▼
Au7o has documented P0599 on 1 BMW model: X1.