How to Find the Coolant Temperature Sensor on a 2015 Jeep Grand Cherokee

If you're searching for the 2015 Jeep Grand Cherokee temperature sensor location, you're likely dealing with overheating warnings, inaccurate temperature readings, or engine performance issues. The primary coolant temperature sensor in this model is located on the rear of the driver-side cylinder head—specifically near the back of the 3.6L Pentastar V6 engine, close to the firewall. This placement makes it less visible from the top, which often leads to confusion during diagnosis or replacement. Knowing the exact position, symptoms of failure, and correct procedures for testing and replacement can save time, prevent misdiagnosis, and avoid unnecessary part replacements.

Understanding the Coolant Temperature Sensor in the 2015 Jeep Grand Cherokee

The coolant temperature sensor (CTS), also known as the engine coolant temperature sensor (ECT), plays a critical role in your vehicle's engine management system ⚙️. It monitors the temperature of the engine coolant and sends real-time data to the powertrain control module (PCM). This information helps regulate fuel mixture, ignition timing, transmission shift points, and operation of the electric cooling fans.

In the 2015 Jeep Grand Cherokee, especially those equipped with the 3.6L V6 engine, there may be more than one temperature sensor. The main CTS is responsible for engine management, while a secondary sensor might feed data to the instrument cluster for driver display purposes. Confusing these two can lead to replacing the wrong component, so accurate identification is essential.

Exact Location of the Coolant Temperature Sensor

📍 Main Coolant Temperature Sensor Location: On the 2015 Jeep Grand Cherokee with the 3.6L V6 engine, the primary CTS is mounted on the rear driver-side (left side) of the cylinder head, just below the intake manifold and near the exhaust manifold heat shield. It sits close to the firewall, making it difficult to access without proper tools and positioning.

To locate it visually:

• Open the hood and stand on the driver’s side of the vehicle.
• Look toward the back of the engine, near where the engine meets the firewall.
• Follow the upper radiator hose to the thermostat housing—it’s on the opposite end of the engine.
• The sensor has a single electrical connector attached and is screwed directly into the cylinder head.
• It typically uses a 3/4-inch or 19mm deep socket for removal.

This rear placement is consistent across many WK2-generation Grand Cherokees (2011–2021), but accessibility varies slightly depending on drivetrain configuration (AWD vs. 4x4) and whether a skid plate or splash shield is installed.

Common Symptoms of a Failing Coolant Temperature Sensor

A faulty coolant temperature sensor doesn't always result in immediate breakdowns, but it can cause a cascade of drivability and efficiency problems ❗. Recognizing early warning signs helps prevent further damage.

Here are the most common symptoms:

• Erratic Temperature Gauge Readings: The dashboard gauge may jump between normal and hot, even if the engine isn’t actually overheating.
• Check Engine Light (CEL): Diagnostic trouble codes such as P0117 (low input), P0118 (high input), or P0125 (insufficient coolant temperature for closed loop) are frequently triggered.
• Poor Fuel Economy: If the sensor reports a falsely low temperature, the PCM enriches the fuel mixture unnecessarily, increasing fuel consumption.
• Difficulty Starting When Cold: A malfunctioning sensor may not signal cold-start conditions correctly, leading to hard starts or extended cranking.
• Overheating Warnings: False high-temperature signals can activate overheat alerts, even when coolant levels and actual temps are normal.
• Fan Run-On or Constant Operation: Cooling fans may run continuously due to incorrect temperature input.

Why Misdiagnosis Is Common

Many owners mistakenly assume that an overheating engine means a bad water pump, thermostat, or radiator. However, a failing CTS can mimic these issues by sending incorrect data to the PCM. Before investing in expensive cooling system repairs, verify the sensor’s output using an OBD2 scanner or multimeter.

Tools and Preparation for Inspection or Replacement

🔧 Replacing the coolant temperature sensor on a 2015 Jeep Grand Cherokee requires careful planning due to its tight location. Here’s what you’ll need:

Tool/Item	Purpose
19mm (3/4") Deep Socket	To remove the sensor from the cylinder head
Swivel Extension & Ratchet	For accessing tight rear-space locations
OBD2 Code Reader	To scan for stored temperature-related codes
Multimeter (Digital)	To test sensor resistance at different temperatures
Coolant Catch Pan & Funnel	To safely drain and refill coolant
New OEM-Style Gasket or Seal	Prevents leaks after reinstallation
Antifreeze (MOPAR Approved)	To refill the system post-replacement
Safety Gloves & Glasses	Protect against hot coolant and sharp edges

Step-by-Step Guide to Accessing and Replacing the Sensor

⏱️ Estimated Time: 1–2 hours
🚗 Skill Level: Intermediate

1. Disconnect the Battery: Always start by disconnecting the negative terminal to prevent electrical shorts.
2. Drain Coolant (Optional but Recommended): While some technicians replace the sensor without draining, removing about 1–2 quarts from the radiator reduces spill risk.
3. Remove Splash Shield (If Necessary): In some models, removing the undercarriage splash shield improves access from below.
4. Access from Top or Bottom? Most experienced mechanics recommend approaching from above using long extensions. However, working from underneath offers better visibility.
5. Unplug Electrical Connector: Locate the wiring harness connected to the sensor and press the release tab to disconnect.
6. Remove the Old Sensor: Use a 19mm deep socket with a swivel adapter to loosen and extract the sensor. Be cautious not to break it off in the head.
7. Install New Sensor: Apply a light coat of high-temperature thread sealant (if not pre-applied) and hand-tighten first, then torque to specification (~18–22 ft-lbs).
8. Reconnect Wiring and Refill Coolant: Bleed air from the system by running the engine with the radiator cap off until flow stabilizes.
9. Clear Codes and Test Drive: Use an OBD2 scanner to erase any stored codes and monitor live data during a short drive.

Differences Between Model Years and Engines

While the general location remains consistent across 2011–2021 WK2 Grand Cherokees, there are minor variations based on engine type:

• 3.6L V6 (Pentastar): Main CTS located on rear driver-side head.
• 5.7L HEMI V8: Uses a similar layout, though some versions have dual sensors—one for PCM and one for gauge.
• 3.0L Diesel: Features additional sensors due to EGR and emissions requirements; location differs slightly.

Always confirm your specific engine type before ordering parts or following repair videos. Using a VIN lookup tool at a dealership or auto parts store ensures compatibility.

Can You Replace the Sensor Without Draining Coolant?

✅ Technically yes—but with caveats. Since the sensor threads directly into the coolant passage, some fluid will leak out during removal. If you work quickly and have a rag ready, losses can be minimal. However, if the engine is warm or pressure exists in the system, expect more spillage. For cleanliness and safety, partial draining is preferred.

Testing the Sensor Before Replacement

Before spending money on a new sensor, verify its condition using a digital multimeter 🔍.

Here’s how:

1. Unplug the sensor’s electrical connector.
2. Set your multimeter to measure resistance (ohms).
3. Probe the two terminals inside the connector.
4. Compare readings to expected values:

Engine Temperature	Expected Resistance (Ohms)
Cold (68°F / 20°C)	~2,500–3,500 Ω
Warm (176°F / 80°C)	~300–500 Ω
Hot (200°F+ / 93°C+)	~150–250 Ω

If resistance doesn’t change with temperature or reads open/infinite, the sensor is faulty.

Common Mistakes to Avoid

🚫 Even experienced DIYers make errors when replacing the CTS on the 2015 Grand Cherokee. Watch out for these:

• Using the Wrong Socket: A standard shallow socket won’t fit. You need a 19mm deep-well socket with a universal joint.
• Over-tightening: Can crack the cylinder head or damage threads. Stick to factory torque specs.
• Ignoring Air Pockets: Failure to bleed the cooling system can cause false overheating and poor heater performance.
• Skipping Diagnostic Steps: Replacing the sensor without checking fuses, wiring, or PCM signals can waste time and money.
• Mixing Up Sensors: Don’t confuse the CTS with the ambient air temperature sensor or oil temperature sensor.

Fuse and Wiring Checks

Before replacing the sensor itself, check related fuses and wiring. Some models route power through the TIPM (Totally Integrated Power Module). Look for blown fuses labeled “Engine Control” or “Cooling Fan.” Inspect the wiring harness for corrosion, chafing, or loose pins at the connector.

Aftercare and System Verification

Once the new sensor is installed, follow these steps to ensure proper function:

• Start the engine and let it reach operating temperature.
• Monitor live data via an OBD2 scanner to confirm rising and stable temperature readings.
• Check for coolant leaks around the sensor base.
• Verify that the temperature gauge moves smoothly.
• Test fan activation—fans should turn on automatically when temp reaches ~210–220°F.

When to Seek Professional Help

While this job is doable for intermediate DIYers, consider professional assistance if:

• You lack the necessary tools or lift access.
• The old sensor breaks off in the head (risk of internal damage).
• You’re unsure about bleeding the cooling system properly.
• Codes return after replacement, indicating deeper electrical or PCM issues.

Long-Term Reliability and Maintenance Tips

The coolant temperature sensor in the 2015 Jeep Grand Cherokee is generally reliable, but exposure to heat cycles and coolant chemistry can degrade it over time. To extend lifespan:

• Use only MOPAR-approved antifreeze or equivalent HOAT formula.
• Flush coolant every 5 years or 60,000 miles to prevent sludge buildup.
• Inspect connectors periodically for moisture or corrosion.
• Address cooling system leaks promptly to avoid contamination.

Frequently Asked Questions

Where is the coolant temperature sensor on a 2015 Jeep Grand Cherokee?

The primary coolant temperature sensor is located on the rear of the driver-side cylinder head, near the firewall, on 3.6L V6 models. It's best accessed from above using a deep socket and swivel extension.

What happens if the temperature sensor fails on my Jeep Grand Cherokee?

A failed sensor can cause poor fuel economy, difficulty starting, incorrect temperature readings, check engine lights, and false overheating warnings. The engine may run rich or trigger limp mode in severe cases.

Can I drive with a bad coolant temperature sensor?

You can drive short distances, but it's not recommended long-term. Incorrect fuel delivery and potential overheating increase wear and risk of engine damage.

Do I need to drain coolant to replace the temperature sensor?

Partial draining is recommended to minimize spills, though some technicians replace it dry with quick movements. Expect minor coolant loss either way.

How do I test the coolant temperature sensor on my 2015 Grand Cherokee?

Use a digital multimeter to measure resistance across the sensor terminals. Compare readings to known values at different temperatures. No change in resistance indicates failure.