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P0198 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


The specific code “P0198 DTC” is assigned to the fuel temperature sensor A’ which is a component of the vehicle’s fuel delivery system. It is a standardized code used in On-Board Diagnostics II (OBD-II) systems to indicate an anomaly related to the fuel temperature sensor.


The OBD II sensor of your vehicle will establish the DTC P0198N code as soon as you detect an unusual reading from the “A” fuel temperature sensor. The sensor shall be responsible for taking fuel temperature readings from the Fuel Rail and transmitting this data to an engine control module, or ECM. This information is helping the ECM set fuel injection timing and optimize engine performance.


The P0198 DTC code may be caused by a number of circumstances, such as:

  • Erroneous Fuel Temperature Sensor: The sensor may be faulty or give erroneous readings as a result of wear and tear or electrical problems.
  • Wiring or Connector Issues: Incorrect data transmission to the ECM may result from damaged or faulty wiring or connections linked to the fuel temperature sensor.
  • Fuel Temperature Sensor Circuit Issues: Problems within the sensor circuit, such as high resistance or short circuits, can lead to erroneous readings.
  • ECM Malfunction: The ECM itself may occasionally malfunction, causing it to interpret data from the fuel temperature sensor incorrectly.


You may encounter one or more of the following symptoms when the P0198 DTC code is activated:

  • Check Engine Light Illumination: The check engine light on your dashboard turning on is the most obvious indication that anything is wrong.
  • Reduced Fuel economy: A defective fuel temperature sensor might mess with the timing of the fuel injection, reducing fuel economy and perhaps impairing engine performance.
  • Engine Performance Problems: You might notice rough idling, stalling, or difficulty starting the engine.


A proficient mechanic or technician will Utilize an OBD-II scanner to get the P0198 DTC code and examine the related freeze frame data. They will next conduct further testing, which could involve:

  • Visual inspection: Examining the fuel temperature sensor and its accompanying components for obvious damage or loose connections.
  • Resistance Testing: Checking for any anomalies by measuring the fuel temperature sensor’s and its circuit’s resistance.
  • Temperature Comparison: To ensure the sensor’s accuracy, compare its values to the actual fuel temperature.
  • Testing the ECM: Making sure it works properly to rule out any computer-related problems.

Common mistakes

During diagnosis, various typical errors might happen, including:

  • Ignoring Other Related Codes: Multiple codes may occasionally show at the same time, therefore, it’s important to avoid concentrating entirely on P0198. The fundamental cause of the issue may be revealed by related codes.
  • Ignoring Wiring Issues: Technicians could focus on sensor-related issues while ignoring wiring or connection issues.
  • Immediate Sensor Replacement: Replacing the sensor right away without first completing a comprehensive test might result in unforeseen costs.

How serious is this?

While the P0198 DTC code may not necessarily cause immediate engine failure, it should not be ignored. A malfunctioning fuel temperature sensor can impact fuel efficiency, emissions, and overall engine performance. Continuously running the vehicle with this issue might exacerbate other components and lead to more significant problems down the road.

What repairs can fix the code?

repair manuals

Depending on the underlying source of the problem, it can be one of the following:

  • Replacing the Fuel Temperature Sensor: If the sensor is found to be faulty or provides inaccurate readings, a replacement is necessary.
  • Fixing Wiring or Connectors: Fixing any faulty or slack connections in the sensor circuit might fix the issue.
  • ECM Replacement: In extremely rare circumstances, an ECM module replacement may be necessary.

Related codes

Codes related to P0198 might include:

  • P0196: Fuel Temperature Sensor “A” Range/Performance
  • P0197: Fuel Temperature Sensor “A” Circuit Low
  • P0199: Fuel Temperature Sensor “A” Circuit Intermittent


If you are faced with a DTC P0198 code, it is possible to be worried, but if you know the ins and outs of this, then an immediate solution can be found. If you encounter the check engine light and retrieve a P0198 code, it is essential to have a qualified mechanic perform a thorough diagnosis to pinpoint the cause accurately. You will be able to keep your vehicle running smoothly and reliably when you take the necessary measures, for example, by replacing a sensor, fixing an electrical issue, or dealing with electronic control module problems.

To avoid any additional complications and to protect the health of your vehicle for a longer time, you should always focus on periodic maintenance and a swift inspection of engine lights.

P0198 Code – What Does It Mean & How To Fix It