The P0198 trouble code on your Jeep Grand Cherokee indicates a fault in the Engine Oil Temperature Sensor Circuit High Input. This code is commonly associated with the 3.0L EcoDiesel V6 engine and can affect the Selec-Terrain system performance and Quadra-Drive traction management.

Common Symptoms

When the P0198 code sets, you may notice the check engine light illuminated on your dashboard. The vehicle may experience reduced fuel economy, hesitation during acceleration, or rough idle characteristics. In some cases, the Selec-Terrain system may default to a specific drive mode, limiting your ability to select different terrain modes. The Quadra-Drive system may also illuminate warning indicators related to 4WD engagement.

For vehicles equipped with the EcoDiesel engine, you might experience delayed throttle response or reduced power output. The Pentastar V6 equipped models often show symptoms during cold weather operation due to sensor sensitivity.

Diagnostic Procedures

Begin diagnosis by connecting a professional scan tool to retrieve all stored trouble codes and freeze frame data. This information helps identify the conditions present when the malfunction occurred. Inspect the related wiring harness for signs of damage, including chafing, connector corrosion, or broken wires, particularly near heat sources like the exhaust manifold.

For the 3.0L EcoDiesel V6 engine, access the specific sensor location and inspect for proper connection. On the 5.7L HEMI V8, the sensor is located in an area prone to moisture accumulation, which can cause intermittent faults. Use a multimeter to verify proper voltage and ground at the sensor connector while monitoring live data.

Component Testing

Test the sensor resistance and voltage output according to manufacturer specifications. Many sensors on the Jeep Grand Cherokee operate within specific temperature-resistance ranges. For example, the MAF sensor on the 3.6L Pentastar should show specific voltage curves as air flow increases. The fuel system sensors on EcoDiesel models require careful attention to the low-pressure fuel system circuit.

Repair Strategies

Replace the faulty sensor or component as needed using OEM-quality replacement parts. Aftermarket sensors may appear identical but often fail prematurely due to inferior construction materials. Always use Mopar or equivalent OEM parts for the Jeep Grand Cherokee to ensure proper integration with the engine control system and Selec-Terrain calibration.

After replacement, clear the trouble codes and perform a drive cycle relearn procedure. The Jeep Grand Cherokee requires the PCM to recalibrate based on the new sensor values. Drive the vehicle through various conditions including highway cruising, city driving, and when equipped, off-road terrain to allow the Selec-Terrain system to relearn optimal settings.

Prevention and Maintenance

Maintain your Jeep Grand Cherokee by using the manufacturer-recommended fuel grade and following the specified service interval for sensor inspection. For the 3.0L EcoDiesel, use only low-sulfur diesel fuel and follow the frequent oil change intervals to prevent fuel system contamination. The 6.2L Supercharged V8 in Trackhawk models requires premium fuel and regular inspection of the supercharger bypass system.

Jeep Grand Cherokee Specific Information

The Jeep Grand Cherokee uses the Selec-Terrain system to coordinate engine output, transmission shift points, and 4WD engagement based on driver-selected modes including Snow, Sand, Mud, and Rock. When sensor faults occur, the system may default to Auto mode, limiting performance optimization for specific terrain conditions.

Quadra-Drive II uses a torque-sensing differential to automatically distribute power to wheels with the most traction. Sensor faults can cause the system to interpret wheel slip incorrectly, resulting in excessive or insufficient power distribution to individual wheels.

Affected Engines and Years

This code commonly affects Grand Cherokee models from 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024 equipped with the 3.0L EcoDiesel V6 engine. The 5.7L HEMI V8 may experience this code after extended idling or frequent short-trip driving. The 3.6L Pentastar V6 is particularly susceptible during extreme temperature conditions. Trackhawk models with the 6.2L supercharged engine may show this code when the supercharger intercooler system experiences thermal stress.

Parts Recommendations

For your Jeep Grand Cherokee, use only high-quality replacement parts that meet Stellantis specifications. OEM sensors, wiring connectors, and control modules ensure proper integration with the Selec-Terrain and Quadra-Drive systems. Avoid generic aftermarket sensors as they may trigger repeated failures or cause drivability issues that affect multiple vehicle systems.

When replacing fuel system components on EcoDiesel models, ensure the replacement parts are specifically designed for the EcoDiesel fuel system to prevent contamination and ensure proper operation of the selective catalytic reduction system.