P0115 on 2024-2026 Jeep Compass: Engine Coolant Temperature Plausibility Fixes

What's Unique About the 2024-2026 Jeep COMPASS

For this specific generation of Jeep Compass with the 2.0L Turbo (GME T4) engine, Jeep has issued a Technical Service Bulletin (TSB) for the P0115 code. The bulletin, #08-115-26 REV. A, directly addresses a "Plausibility Check" failure and potential overheating warnings. [⭐ MANUFACTURER TSB — highest authority] This indicates a known issue recognized by the manufacturer, making a faulty sensor a higher-than-usual probability compared to other vehicles where wiring or other components might be equally likely culprits. The 2.0L GME T4 engine is also known for cooling system issues, such as cracked coolant reservoirs due to proximity to the turbo 🎬 Watch: Diagnose and repair common 2.0T engine overheating issues., which can lead to low coolant levels and trigger this code.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light (Malfunction Indicator Lamp) is on. [⭐ MANUFACTURER TSB — highest authority]
• Engine overheating warning light may be illuminated. [⭐ MANUFACTURER TSB — highest authority]
• Engine temperature gauge reading incorrectly, fluctuating, or dropping out completely.
• Cooling fans running constantly at high speed, even when the engine is cold.
• Reduced fuel economy.
• Difficulty starting the engine, especially when cold.
• Black smoke from the exhaust.
• Rough idle or poor engine performance.

Most Likely Causes

1. Faulty Engine Coolant Temperature (ECT) Sensor 🔴 High Probability A manufacturer TSB (#08-115-26 REV. A) exists for this exact code and symptom, pointing towards issues with the ECT sensor itself. [⭐ MANUFACTURER TSB — highest authority] Forum discussions for this generation Compass confirm that dealers often replace the ECT sensor to resolve the P0115 code, sometimes very early in the vehicle's life.
   How to confirm: Use a scan tool to compare the ECT reading to the Intake Air Temperature (IAT) on a cold engine; they should be within a few degrees of each other. If the ECT reading is irrational (e.g., -40°F or 280°F), the sensor is bad.
   Typical fix: Replace the Engine Coolant Temperature sensor. This involves draining some coolant, unscrewing the old sensor, installing the new one, and topping off/bleeding the cooling system. The OEM Mopar part number is reported to be 68527252AA. 🎬 Watch: Understanding the causes and fixes for the P0115 code.
   Est. part cost: $20-$60
2. Low Engine Coolant Level 🟡 Medium Probability The 2.0L Turbo engine in the Compass is known for a potential issue where the plastic coolant reservoir, located near the hot turbocharger, can develop hairline cracks and leak coolant. This slow leak can cause the coolant level to drop, exposing the sensor to air and causing implausible readings.
   How to confirm: Visually inspect the coolant reservoir and radiator (when the engine is cold) to ensure the coolant is at the proper level. Look for pink, crusty residue around the reservoir bottle, which indicates a slow leak.
   Typical fix: Find and repair the source of the coolant leak (e.g., replace the coolant reservoir), then refill and bleed the cooling system with the correct type of coolant.
   Est. part cost: $20-$50 for coolant, plus cost of leak repair if needed.
3. Wiring or Connector Issue ⚪ Low Probability Early production runs of the GME T4 engine were noted to have some quality control issues with sensor connections.
   How to confirm: Visually inspect the ECT sensor's electrical connector and wiring harness for damage, corrosion (green crust), or loose pins. A multimeter can be used to check for continuity and proper voltage at the connector.
   Typical fix: Clean the connector terminals or repair/replace the damaged section of the wiring harness.
   Est. part cost: $5-$100 depending on the extent of the repair.
4. Stuck Thermostat ⚪ Low Probability
   How to confirm: Monitor the ECT sensor data on a scan tool as the engine warms up. If the temperature rises very slowly and never reaches normal operating temp (stuck open), or if it overheats quickly (stuck closed), the thermostat is likely at fault. This can also trigger code P0128.
   Typical fix: Replace the thermostat and gasket, then refill and bleed the cooling system.
   Est. part cost: $30-$80

Rare But Worth Checking

• Air Pocket in the Cooling System: If the cooling system was recently serviced (e.g., coolant flush or component replacement), an air pocket trapped near the ECT sensor can cause erratic readings. Bleeding the system properly can resolve this.
• Faulty Powertrain Control Module (PCM): This is extremely rare and should only be considered after all other possibilities (sensor, wiring, coolant level, thermostat) have been definitively ruled out. Sometimes a software update is required to fix logic errors.

Diagnosis Steps

1. Check the engine coolant level in the reservoir and radiator (only when the engine is completely cool). Inspect the reservoir for any signs of cracking or pink residue.
2. Connect an OBD-II scanner. With the engine cold and off, compare the Engine Coolant Temperature (ECT) and Intake Air Temperature (IAT) readings. They should be within 5°F (3°C) of each other.
3. Start the engine and monitor the ECT reading on the scanner. It should climb steadily and smoothly as the engine warms up to its operating temperature (typically 190-220°F).
4. If the reading is erratic, stuck, or clearly incorrect (e.g., -40°F), the sensor is the primary suspect.
5. Visually inspect the ECT sensor's connector and wiring for any signs of corrosion, damage, or loose connections.
6. If the sensor and wiring appear fine, but the engine temperature is abnormal (overheating or running too cool), investigate the thermostat's operation by feeling the upper radiator hose to see if it gets hot as the engine reaches operating temperature.
7. If all other components check out, perform resistance tests on the sensor and continuity tests on the wiring back to the PCM as a final verification before considering a PCM fault.

Parts You'll Likely Need

• Engine Coolant Temperature Sensor (OEM #68527252AA) — This is the most common failure point for code P0115 on this vehicle, as supported by manufacturer TSBs and owner forums.
  Trusted brands: Mopar, NTK, Delphi
  OEM price range: $40-$70
  Aftermarket price range: $20-$50

Related Codes That Often Appear With This One

• P0117 — Indicates the ECT sensor circuit input is low (short to ground), which is a specific type of failure that can trigger the general P0115 code.
• P0118 — Indicates the ECT sensor circuit input is high (open circuit), another specific failure mode that can lead to a P0115.
• P0128 — Indicates the thermostat is not allowing the engine to reach operating temperature within a calculated time. A faulty ECT sensor can provide the incorrect data that leads to this code being set.
• P00B6 — Indicates a correlation problem between the radiator coolant temp sensor and the engine coolant temp sensor, which can be logged alongside P0115 if the PCM sees conflicting data between its temperature inputs.

Technical Service Bulletins (TSBs) & Recalls

• 08-115-26 REV. A: Addresses MIL illumination for P0115-00 and potential overheating warnings, pointing to a plausibility check failure of the ECT sensor. While originally issued for 2022-2023 models, it applies to the same engine and fault in 2024+ models.

Platform-Specific Known Issues

• TSB #08-115-26 REV. A notes that customers may experience MIL illumination with DTC P0115-00 (Engine Coolant Temperature Plausibility Check) and may also see an engine overheating warning lamp. [⭐ MANUFACTURER TSB — highest authority]
• Owner Experience: A user on the r/JeepCompass subreddit with a 2018 model (same engine family) experienced coolant temperatures reaching 230-240 degrees. After replacing a leaking reservoir and a faulty thermostat, the temperature gauge issues were resolved, highlighting how multiple cooling system components can contribute to the problem.

Mechanic-Grade Diagnostic Values

• ECT Sensor Resistance (typical NTC sensor) — expected: ~2000-3000 Ω at 20°C (68°F), dropping to ~200-300 Ω at 90°C (194°F).. Failure: Infinite resistance (open circuit), zero resistance (short circuit), or readings that don't change with temperature.
• ECT Sensor Signal Voltage (Key On, Engine Off, Cold Engine) — expected: 2.0V to 3.0V, depending on ambient temperature.. Failure: Voltage near 5.0V may indicate an open circuit or bad ground. Voltage near 0V indicates a short to ground.
• ECT Sensor Signal Voltage (Engine at Operating Temp) — expected: Approximately 0.5V to 1.2V.. Failure: Voltage remains high (e.g., over 2.0V) when the engine is fully warmed up.
• PCM Fail-Safe Value — expected: If the ECM detects DTC P0115, it operates a fail-safe function where the engine coolant temperature is assumed to be 80°C (176°F).. Failure: This is not a failure indicator, but knowledge of this default value helps explain engine behavior (like constant fan operation) when the code is active.

Scan Tool Commands That Help

• OBD-II Scan Tool (Generic) or wiTECH (OEM): Read Freeze Frame Data — Use to see the exact engine conditions (coolant temp, RPM, speed, etc.) at the moment the P0115 code was triggered. This can help determine if the fault occurs when cold, hot, or intermittently.
• OBD-II Scan Tool (Generic) or wiTECH (OEM): Clear/Reset DTCs — After a repair (like replacing the sensor or fixing wiring), this command is used to clear the MIL and stored code. The vehicle must then be driven through a full drive cycle to confirm the fix.

Wiring & Ground Locations

• ECT Sensor Connector — Typically screwed into the thermostat housing or the cylinder head on the 2.0L Turbo engine.. The two-wire connector provides the 5V reference voltage from the PCM and the return signal. Corrosion (green crust) or damage to the pins or wires at this connector is a common cause of circuit-related codes like P0115, P0117, and P0118.
• G104 (Example Ground) — On similar Jeep engine platforms, a key ground point (like G104) is located on the rear or side of the engine block.. Multiple sensors, including O2 sensors and sometimes the circuit path for the ECT sensor, share a common ground point. If this ground stud becomes corroded or loose, it can cause high resistance and trigger multiple 'circuit high' or 'plausibility' codes simultaneously. If P0115 appears with other sensor codes, checking shared grounds is critical.

Real Owner Repair Stories

• FIAT Forum user (Fiat Grande Punto (demonstrates common intermittent electrical fault)) — P0115 code would return every other week, causing the radiator fan to run erratically. The code could be cleared but would always come back.
  ❌ Tried (didn't work) Replacing the Engine Coolant Temperature sensor.
  ✅ What actually fixed it The issue was suspected to be a bad electrical connection. The final advice that resolved similar issues for others was to pull the plugs on the sensor and the ECU, check for corrosion, clean with contact cleaner, and check the main engine-to-chassis ground strap.
• FIAT Forum user (Fiat Panda (demonstrates intermittent self-clearing fault)) — Check engine light came on and temperature gauge went dead. Scan showed P0115. Later, the light went out and the gauge started working again on its own.
  ❌ Tried (didn't work) No parts were replaced initially.
  ✅ What actually fixed it The owner cleaned the ECT sensor connector with contact cleaner and applied a small amount of vaseline (dielectric grease is professionally recommended) as a preventative measure. The intermittent fault did not immediately return, pointing to a temporary poor connection as the likely cause.