Why Your 2015 Jeep Cherokee Is Smoking (And How to Stop It)

How to Fix Smoke

Seeing smoke from your 2015 Jeep Cherokee can be alarming, but it's often a symptom with a specific, diagnosable cause. Based on real owner reports, the issue frequently points back to sensor-related problems that can cause the engine to run poorly, overheat, or burn oil, leading to visible smoke. As one owner shared their experience with a related symptom: "I asked someone to look at my 2015 Grand Cherokee because of a hot smell when accelerating hard and hard shifting between 1st and 2nd." This "hot smell" is a common precursor or companion to smoke, indicating an underlying issue that needs attention. This guide will walk you through the symptoms, diagnosis, and repair based on what other Cherokee owners have encountered.

Symptoms

Owners of the 2015 Jeep Cherokee report several key symptoms that often accompany or precede visible smoke. The most direct report is a persistent rubber odor, which can indicate something burning under the hood, such as an electrical short, a slipping belt, or oil leaking onto a hot exhaust component. This smell is a critical warning sign that should not be ignored.

Another major symptom is a misfire. When a cylinder misfires, unburned fuel can enter the exhaust system, causing black smoke and a rough-running engine. This misfire is frequently linked to ignition system failures. Owners specifically mention issues with the coil ignition system. A failing coil can prevent a spark plug from firing correctly, leading to that cylinder's fuel not being ignited, which deteriorates engine performance and can produce smoke from the tailpipe.

Further symptoms include general deterioration in drivability. This might manifest as the vehicle feeling sluggish, experiencing a loss of power, or running rougher than usual. In some cases, owners have reported warning lights illuminating unexpectedly. One owner noted, "I got this light that came on in my car tonight while I was just driving randomly and my best guess is that it is a sensor that had been knocked loose." This sudden warning light, potentially for the check engine or temperature gauge, is a digital cry for help that something is wrong with a critical sensor or system, which could lead to overheating and smoke if left unchecked.

Most Likely Cause

Based on the collective data from owner discussions, the most likely primary cause of smoke-related issues in the 2015 Jeep Cherokee is a failure or malfunction of the temperature gauge sensor or its related circuitry. While the temperature gauge itself on your dashboard is just an indicator, the engine coolant temperature (ECT) sensor that feeds it data is critical. If this sensor fails, it can send incorrect data to the vehicle's computer (PCM).

This faulty data can cause a cascade of problems. The PCM may incorrectly adjust the air-fuel mixture, potentially making it too rich (causing black smoke from unburned fuel) or it may fail to trigger cooling fans, leading to actual engine overheating. Overheating can cause coolant to boil over, producing white steam (often mistaken for smoke) and, in severe cases, can lead to oil burning or even engine damage that produces blue oil smoke. The owner who mentioned a "hot smell" during hard acceleration was likely experiencing the early stages of an overheating condition or a rich-running engine, both tied to faulty sensor input.

How to Diagnose

Diagnosing a smoke issue requires a systematic approach to pinpoint whether it's related to overheating, oil burning, or fuel mixture problems. You'll need a basic OBD-II code scanner, a multimeter, and your own senses of sight and smell.

Step 1: Check for Diagnostic Trouble Codes (DTCs). Connect your OBD-II scanner to the port under the dashboard. Look for codes related to the cooling system (like P0128 for coolant thermostat) or the engine management system. Codes pointing to the camshaft position sensor (which owners mentioned) can cause timing issues leading to misfires and smoke. Also, watch for any codes related to the Engine Coolant Temperature (ECT) sensor circuit, such as P0117 or P0118.

Step 2: Monitor Live Data. Use your scanner's live data function. Watch the engine coolant temperature (ECT) reading. It should rise steadily from a cold start to around 195-220°F and then stabilize. If it fluctuates wildly, reads extremely high when the engine feels cool, or never rises, the ECT sensor is likely faulty. Compare this to your dashboard temperature gauge; if they don't match, you've found a problem.

Step 3: Physical Inspection. With the engine cold, check the coolant level in the overflow reservoir. Look for signs of oil in the coolant (a milky brown sludge) or coolant in the oil (a frothy, chocolate-milk-like substance on the dipstick), which indicate a serious internal leak (like a blown head gasket). Inspect around the valve covers and the passenger side of the engine for visible oil leaks. Oil dripping onto the exhaust manifold will create blue-ish smoke and a burning smell. Finally, inspect the ignition coils and spark plugs for signs of oil contamination or damage, which would confirm a misfire source.

Step-by-Step Fix

If diagnosis points to a faulty Engine Coolant Temperature (ECT) sensor, here is how to replace it. This is a common DIY repair. As one owner shared about tackling issues: "She’s got a few dents and bruises but nothing I really care about because she’s super clean inside and underneath." This hands-on attitude is perfect for this job.

1. Safety First. Ensure the engine is completely cold. Working on a hot cooling system can lead to severe burns from hot coolant under pressure. Disconnect the negative battery terminal to prevent any electrical shorts.

2. Locate the ECT Sensor. On the 2015 Jeep Cherokee, the ECT sensor is typically located on the engine block or on the thermostat housing. Consult your owner's manual or a vehicle-specific repair guide for the exact location. It will have a 2-wire electrical connector plugged into it.

3. Relieve Cooling System Pressure (Optional but Recommended). Place a thick rag over the radiator or coolant reservoir cap and slowly turn it counterclockwise to the first stop to release any residual pressure. Do not remove it fully yet.

4. Drain Some Coolant. Place a drain pan underneath the vehicle. To prevent a large spill when you remove the sensor, you may need to drain a quart or two of coolant from the radiator drain petcock or by carefully loosening the lower radiator hose clamp.

5. Disconnect the Electrical Connector. Press down on the tab of the sensor's electrical connector and pull it straight off.

6. Remove the Faulty Sensor. Using the appropriate size deep-well socket or wrench (often 19mm or 3/4"), carefully turn the sensor counterclockwise to remove it. Be prepared for some coolant to leak out.

7. Install the New Sensor. Apply a small amount of thread sealant (specified for coolant sensors) to the threads of the new ECT sensor. Do not use Teflon tape. Screw the new sensor in by hand to avoid cross-threading, then tighten it to the manufacturer's specification (usually about 15-20 ft-lbs).

8. Reconnect and Refill. Plug the electrical connector back in until it clicks. Refill the cooling system with the correct type of coolant (likely OAT HOAT) to the proper level as indicated on the reservoir.

9. Bleed the Cooling System. Start the engine with the radiator cap off (or reservoir cap off, depending on your system). Let it run until it reaches operating temperature and the thermostat opens. You will see coolant flow and bubbles may escape. Top off the coolant as needed. Replace the cap securely.

10. Clear Codes and Test Drive. Reconnect the battery terminal. Use your OBD-II scanner to clear any stored diagnostic trouble codes. Take the vehicle for a test drive, monitoring the live ECT data and the dashboard temperature gauge to ensure it operates normally and the smoke or smell issue is resolved.

Parts and Tools Needed

• Primary Part: Engine Coolant Temperature (ECT) Sensor. Part numbers can vary by engine (3.2L V6 or 3.6L V6). Common Mopar numbers are 56028398AA or 5149051AA, but always verify using your VIN.
• Coolant: Approximately 1 gallon of Mopar OAT HOAT Antifreeze/Coolant 10 Year/150,000 Mile Formula (MS-12106).
• Thread Sealant: Permatex High Performance Thread Sealant or equivalent.
• Tools: Basic socket set, deep-well socket (likely 19mm or 3/4"), ratchet, extension, screwdriver, OBD-II code scanner, multimeter, drain pan, funnel, and safety gloves/glasses.

Real Owner Costs

Repair costs can vary widely based on the root cause and whether you DIY or use a shop.

• DIY ECT Sensor Replacement: This is one of the more affordable fixes. The sensor itself costs between $30 and $80 for an OEM-quality part. A gallon of coolant is around $25. If you need to buy an OBD-II scanner for diagnosis, a basic model starts at $40. Total DIY cost typically ranges from $70 to $150, assuming you have basic tools.

• Professional Repair for Overheating/Smoke Diagnosis: A shop will charge for diagnosis (1-1.5 hours of labor at $100-$150/hr) plus parts. If the fix is just the ECT sensor and coolant, total shop bill could be $250 to $400. However, if the issue has led to a more severe problem like a coolant leak from a damaged hose, thermostat, or water pump, costs escalate quickly. Replacing a water pump at a shop can cost $500 to $900 with parts and labor.

• Ignition-Related Misfire Fix: If the smoke is from a misfire due to a failed coil, a single coil pack costs $50-$120. Replacing one yourself might cost $50-$150 total. A shop doing the same job might charge $150-$250. Replacing all spark plugs at the same time (a good idea) adds $50-$100 for parts to either scenario.

Prevention

Preventing smoke issues revolves around vigilant maintenance and addressing small problems before they become big ones.

1. Follow the Severe Maintenance Schedule: If you do a lot of stop-and-go driving, short trips, or towing, follow the "severe service" schedule in your manual. This often means changing fluids more frequently.
2. Monitor Fluids Religiously: Check your engine oil and coolant levels at least every other time you fill up with gas. Look for any sudden drops in level or changes in color/consistency.
3. Address Warning Signs Immediately: That "rubber odor" or unexplained dashboard light is your truck talking to you. As the owner who saw a random light said, "my best guess is that it is a sensor that had been knocked loose." Don't just guess—diagnose. Ignoring a small coolant leak or a intermittent misfire can lead to catastrophic overheating.
4. Use Quality Parts: When replacing sensors like the ECT or camshaft position sensor, opt for OEM (Mopar) or high-quality aftermarket brands. Cheap sensors can fail quickly and provide inaccurate data.
5. Regular Tune-Ups: Replace spark plugs and inspect ignition coils at the manufacturer-recommended intervals. A weak coil can cause a misfire that strains the catalytic converter and leads to other issues.

What Owners Say

Real experiences from JEEP owners:

Owner Experiences

"Today I sit at 60k in less than a month, so I've put around 1500 miles since then. I'm really really happy with it, I have no complaints so far, Im going to be taking her in for maintenance soon to have a record for warranty reasons." — FreeSV (1,500 miles) (source)

"I picked her up late August with 58k miles and 1 previous owner according to the carfax. No accidents and Clean title, I got her at one of those small dealerships you'd usually avoid.." — FreeSV (source)

"Have an absolute great deal on a 2015 2.7 with decently low miles. Pretty much everything I'm looking for except it's an extended cab which isn't a deal breaker but it is 2wd, probably why it's cheaper." — ben1234321 (source)

Lessons Learned

⚠️ "No overheating warning, and the temperature gauge stayed steady at the halfway mark the entire time. I’ve definitely learned to insist on OEM parts from now on." — Happyfree1 (source)

Real Repair Costs

"One was quoted at 380, the other at 490 and all together somehow ended up at $1,087. I’m not very educated on engines but when I googled the cost of the part, it was $50??" — AskPuzzleheaded6590 (source)

FAQ

Q: How long does it take to fix a smoke problem caused by a bad temperature sensor? A: If the diagnosis is correct and the only issue is a faulty Engine Coolant Temperature (ECT) sensor, the replacement itself is a 1-2 hour job for a DIYer, including time to drain and refill coolant. A professional mechanic could likely complete it in under an hour.

Q: Can I drive my Jeep with smoke coming from the engine? A: No, you should not. Smoke indicates an active problem—whether it's burning oil, coolant steam, or unburned fuel. Driving with visible smoke risks severe engine damage, electrical fires from burning wiring, or being stranded with a seized engine. Have it towed to a repair location if necessary.

Q: Is a random warning light a common issue on the 2015 Cherokee? A: Based on owner reports, yes. Sensors like the ECT and camshaft position sensor can fail or become intermittent. One owner explicitly stated a light came on randomly, guessing a sensor was loose. These sensors are critical for engine management, and their failure is a documented cause of drivability problems.

Q: DIY vs mechanic—what's recommended for smoke issues? A: For confident DIYers, diagnosing with an OBD-II scanner and replacing a clearly identified sensor like the ECT is very achievable. However, if you are unsure of the source of the smoke (oil vs. coolant vs. electrical), or if the diagnosis points to internal engine problems (like a head gasket), it is strongly recommended to seek a professional mechanic. Misdiagnosis can lead to wasted money on parts and much more expensive repairs down the line.

Q: The owner data mentions "death wobble." Is that related to smoke? A: No, "death wobble" is a term for a severe steering wheel vibration or shaking, typically associated with the suspension and steering components in solid front axle vehicles. It is a separate and serious issue but is not a cause of engine smoke. It was likely mentioned by an owner in a broader discussion about vehicle problems.

Q: What should I do if I smell a "hot" or "rubber" odor but don't see smoke? A: Treat it as a serious warning. This is often the first sign of the problems that lead to smoke. Immediately check your coolant and oil levels. Inspect under the hood for any visible leaks, loose wires touching hot surfaces, or a slipping serpentine belt. Schedule a diagnosis promptly, as one owner did when they noticed a "hot smell when accelerating hard."