P0599 on Dodge: How to Diagnose & Fix
Thermostat Heater Control Circuit High
1 Dodge model · 1 documented issue · 1 critical · $100-$800 repair
P0599 on Dodge by model: symptoms, diagnosis and fix
Calibers are prone to overheating from radiator fan failure, thermostat sticking, water pump failure, and radiator clogging. Same cooling system shared with Jeep Compass/Patriot (PM/MK platform). Fan relay failure is the most common single cause.
Common Symptoms
- Temperature gauge climbing above normal at idle
- A/C compressor disengaging from high temps
- Coolant leak
- Steam from engine bay
- CVT overheating simultaneously
How to Fix
Check fan relay first, then fan motor, thermostat, water pump, and radiator. Engine cooling and CVT cooling are interconnected - overheating engine can cause CVT overheating and vice versa.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Mopar 68053218AA five-pin mini relay
Fan-control relay branch only after the exact TIPM cavity/function and failed electrical test are confirmed Fitment: Live OEM fitment lists 2008-2012 Caliber; 2007 uses a different relay family and remains VIN/fuse-map confirmation only …
- Dorman 621-029 dual radiator cooling fan assembly without controller
Fan-motor/module branch after commanded-fan, power, ground and current-draw tests confirm the complete assembly is faulty Fitment: Manufacturer application for the Caliber platform; compare connector and A/C/fan configuration, especially…
- Mopar 55111016AC primary engine coolant thermostat
Thermostat branch only after temperature testing confirms a stuck thermostat rather than airflow, pump, radiator or combustion-gas trouble Fitment: Live fitment covers 2007-2012 Caliber 1.8L/2.0L/2.4L; verify whether the repair also requ…
- Mopar 68046026AA engine water pump
Water-pump branch when pressure testing, bearing inspection or circulation testing confirms pump failure Fitment: Live OEM fitment lists 2007-2012 Caliber 1.8L, 2.0L and 2.4L including SRT-4; pump only, so check gasket/pulley requirement…
- Mopar 68004049AB engine cooling radiator
Radiator branch after flow, temperature-drop, pressure and external-fin inspection confirm restriction or leakage Fitment: Live OEM fitment lists 2007-2012 Caliber 1.8L/2.0L/2.4L across non-SRT trims; SRT-4 is not shown and remains exclu…
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Sources for this issue (1)
P0599 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 P0599 mean on a Dodge?
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 Dodge it is documented across 1 model: Caliber.
What are the most common causes of P0599?
The most common causes of P0599 are: 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). The specific cause varies by vehicle.
How much does it cost to fix P0599 on a Dodge?
Published repair estimates on Dodge range from $100 to $800 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 P0599 on a different make?
View P0599 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.