P0128 on Jeep Cherokee
Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Jeep Cherokee context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0128.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What P0128 Means on Your Jeep Cherokee
P0128 is a diagnostic trouble code indicating: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). This code relates to the fuel and air metering system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real Jeep Cherokee Owner Reports
Source: NHTSA Complaints Database
"Cei p0128 coolant temperature too cold. no overheating issues, temps have remained consistently. came on while driving. thermostat needs replacing in only 4 years from purchase. temps have only been hovering around freezing."
"Cei p0128 coolant temperature too cold. having to replace thermostat on a car only 3 years old. temps have not been below freezing & didn't have this issue last winter. thermostat is stuck open so gas consumption has increased & heat has decreased."
"Engine and car was not warming up with remote start. Finally check engine light comes on. Code P0128 thermostat. Repaired 1/28/2021 @ 85762 miles. All antifreeze replaced. $600+ repair. 2/1/2022 same observed failure of engine to warm up during remote starts."
"'shifter bezel and wiring requires replacement according to eide chrysler service techs 'shift module not functioning ' replaced by eide chrysler twice 'vehicle randomly swaps between r/n/d while driving 'vehicle has difficult time starting 'check engine light ' code p0128 ' coolant temperature"
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Jeep Cherokee
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.