P0598 on Jeep: How to Diagnose & Fix
Thermostat Heater Control Circuit Low
3 Jeep models · 4 documented issues · 1 critical · $60-$1,000 repair
P0598 on Jeep by model: symptoms, diagnosis and fix
The plastic thermostat housing on the 2.0L and 2.4L World engines cracks from heat cycling, causing coolant leaks and potential engine overheating. This is the same design flaw shared with the Jeep Compass and Dodge Caliber that use the same engine family. The plastic becomes brittle over time and cracks at the O-ring seal area.
Common Symptoms
- Coolant leak near thermostat on engine
- Low coolant warning light
- Engine overheating
- Sweet coolant smell under hood
- White crusty residue around thermostat area
- Temperature gauge runs hot
How to Fix
Replace the plastic thermostat housing with the upgraded aluminum version. OEM part number 68003582AB or aftermarket Dorman 902-319 ($30-60). The aluminum housing eliminates the cracking problem permanently. The assembly includes the housing, thermostat, temperature sensor, and O-ring. Parts cost $30-80, labor 1-2 hours. Very DIY-friendly repair with basic tools.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Dorman 902-319 engine-coolant thermostat housing assemblyOEMDorman 902-319
Plastic housing/thermostat/O-ring assembly replacement when the matching five-port housing is confirmed leaking or damaged Fitment/availability: 2007-2017 Patriot 2.0L/2.4L; 2007-2008 requires the later 2009-and-newer heater-hose design,…
- Genuine Mopar 68676479AA upper thermostat-housing coverOEMMopar 68676479AA
OEM upper-cover replacement when the pressure-tested leak is isolated to that catalog branch Fitment/availability: Current upper-cover supersession for 4884571AB on specified Patriot 2.0L/2.4L applications; confirm VIN because catalog ye…
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Owner tips & cautions
- TipThis is an easy DIY repair - drain some coolant, remove 2 bolts, swap housing, refill and bleed air from system
Sources for this issue (1)
Beyond the thermostat housing issue, the Patriot suffers from additional cooling system failures including water pump failure, radiator fan motor burnout, and radiator cap failure. The water pump can develop an internal leak that mixes coolant into the engine oil, causing severe engine damage. The radiator fan may stop working intermittently, leading to overheating in slow traffic or idle.
Common Symptoms
- Temperature gauge in red zone
- Coolant boiling over from reservoir
- Radiator fan not spinning at idle
- Milky/frothy oil on dipstick (water pump failure)
- Steam from under hood
- Heater blowing cold air
How to Fix
Replace the water pump (Mopar 04884319AH for 2.4L, $50-80 part) at 80,000-100,000 miles as preventive maintenance. Check coolant for oil contamination (milky appearance). Replace radiator fan assembly if failing ($200-350, Dorman 620-046). Replace radiator cap annually ($5-10, Stant 10230). Flush and replace coolant every 30,000 miles with Mopar OAT coolant.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 68046026AA water pumpOEMMopar 68046026AA
Water-pump replacement after external leakage, bearing damage or failed circulation is confirmed Fitment/availability: 2007-2010 and 2012-2017 Patriot 2.0L/2.4L catalog fitment; confirm 2011 and every VIN before ordering.
- Genuine Mopar 68046028AA water-pump gasketOEMMopar 68046028AA
New sealing gasket when the matching water pump is removed Fitment/availability: 2007 Patriot 2.0L/2.4L catalog listing and related World-engine pump branch; confirm VIN/current supersession.
- Dorman 621-029 radiator/condenser fan assemblyOEMDorman 621-029
Confirm exact build before purchase.
- Genuine Mopar 4596198 radiator pressure capOEMMopar 4596198
2007-2008 uses a different lookup; do not replace annually without a failed test.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- WarningIf you see milky oil on the dipstick, stop driving immediately - the water pump is leaking coolant into the oil and engine damage is occurring
- TipReplace the radiator cap annually as preventive maintenance - a weak cap reduces cooling system pressure and causes premature boilover
Sources for this issue (1)
The plastic thermostat housing on the 2.0L and 2.4L World engines is prone to cracking and leaking coolant. The housing warps from heat cycling, causing the O-ring seal to fail. This leads to external coolant leaks, overheating, and potential engine damage if not addressed. The same housing is used across Compass, Patriot, and Dodge Caliber platforms.
Common Symptoms
- Coolant leak near thermostat area
- Low coolant warning light
- Engine overheating
- Sweet smell of coolant under hood
- White residue or stains around thermostat housing
- Temperature gauge running higher than normal
How to Fix
Replace the thermostat housing assembly with the updated aluminum version (OEM 68003582AB, aftermarket Dorman 902-319). The aluminum housing is far more durable than the original plastic unit. The assembly includes housing, thermostat, temperature sensor, and O-ring. Parts cost $40-80, labor 1-2 hours. This is a common DIY repair.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Dorman engine-coolant thermostat housing assemblyOEMDorman 902-319 / OE cross 68003582AB
A pressure-test-confirmed crack, warp or seal leak at the matching thermostat outlet on a 2007-2017 first-generation MK Compass Fitment/availability: Dorman 902-319 cross-references 68003582AB and is cataloged for the 2007-2017 Compass.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipThis is a straightforward DIY repair - drain some coolant, remove 2 bolts, swap housing, refill and bleed
Sources for this issue (2)
The Commander is susceptible to engine overheating caused by failing water pumps, cracked radiator tanks, leaking heater core connections, and thermostat failures. The radiator end tanks (plastic) are prone to cracking at the seam where they meet the aluminum core. Power steering cooler line leaks can also compound cooling issues. The 4.7L V8 is especially vulnerable.
Common Symptoms
- Temperature gauge runs hot or in red zone
- Coolant leak visible under vehicle
- Steam or sweet smell from under hood
- Low coolant warning light
- Heater blows cold air intermittently
- Coolant puddle at front of vehicle
How to Fix
Replace the thermostat and housing as preventive maintenance ($50-150). Upgrade to an all-aluminum radiator (Mishimoto or CSF) to eliminate plastic tank cracking ($200-400). Replace the water pump at 80,000-100,000 miles as preventive maintenance (Mopar 53021429AB for 3.7L, 53021578AD for 4.7L). Check and replace coolant hoses that show swelling or cracking. Flush cooling system every 30,000 miles.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Mishimoto direct-replacement radiator for 3.7L/4.7L CommanderOEMMishimoto R2839-MT
A pressure-tested crack, leak or confirmed restriction in the radiator on a compatible 3.7L or 4.7L Commander Fitment/availability: R2839-MT explicitly fits 2006-2010 Commander 3.7L and 2006-2009 4.7L.
- Mopar water pump for 3.7L/4.7L PowerTech enginesOEMMopar 53022189AH (supersedes 53022189AC)
A confirmed leaking, noisy, loose or non-circulating water pump on a compatible 3.7L or 4.7L Commander Fitment/availability: 53022189AH supersedes 53022189AC for the 3.7L/4.7L branch. Confirm VIN/model year, included gasket and current s…
- Mopar/Crown water pump for early 5.7L HEMIOEM4792838AB
A confirmed water-pump failure on a 2006-2008 Commander 5.7L HEMI Fitment/availability: 4792838AB is explicitly cataloged for the early 5.7L Commander branch. Do not use it for the revised 2009-2010 5.7L system or for 3.7/4.7 engines.
- Mopar water pump for 2009-2010 5.7L HEMI VCTOEMMopar 53022095AJ (supersedes 53022095AF)
A confirmed water-pump failure on a 2009-2010 Commander 5.7L HEMI VCT Fitment/availability: 53022095AJ supersedes 53022095AF for the later 5.7L HEMI VCT branch. Confirm VIN and current supersession; it is not interchangeable with the 200…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipReplace the radiator proactively with an all-aluminum unit before the plastic tanks crack - it is a matter of when, not if
Sources for this issue (1)
P0598 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 P0598 mean on a Jeep?
P0598 stands for "Thermostat Heater Control Circuit Low." This code applies to engines with an electronically controlled (heated) thermostat and means the Powertrain Control Module detected an abnormally low voltage in the thermostat heater control circuit. The heater element lets the computer fine-tune coolant temperature for efficiency and emissions by opening the thermostat sooner under certain conditions. P0598 sets when the control or feedback circuit reads lower than expected (often a short to ground or loss of supply). It is found mainly on certain European makes (BMW, Mercedes, VW/Audi, etc.) and usually has little effect on driving. On Jeep it is documented across 3 models: Patriot, Compass, Commander.
What are the most common causes of P0598?
The most common causes of P0598 are: Faulty electronically controlled (map-controlled) thermostat, Short to ground in the heater control wiring, Corroded or loose thermostat connector, Open or damaged wiring in the control circuit, Low coolant level overheating the thermostat heater, Blown fuse or poor power supply to the circuit, Faulty PCM control driver. The specific cause varies by vehicle.
How much does it cost to fix P0598 on a Jeep?
Published repair estimates on Jeep range from $60 to $1,000 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 P0598 on a different make?
View P0598 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.