The Comprehensive Guide to the P1844 DTC Code


In the world of automotive diagnostics, understanding Diagnostic Trouble Codes (DTCs) is crucial. Among the vast array of DTCs, the P1844 code holds significant importance. This article aims to provide a comprehensive guide to the P1844 DTC code, covering its definition, causes, symptoms, diagnosis, and potential solutions.

What is the P1844 DTC Code?

The P1844 DTC code, also known as Transmission Fluid Pressure Sensor/Switch D Circuit, indicates a malfunction in the transmission fluid pressure sensor or switch circuit within the vehicle’s transmission system. The code originates from the Powertrain Control Module (PCM) when it identifies an inconsistency or fault in the sensor’s circuit.

Common Causes of the P1844 DTC Code

Several factors can trigger the P1844 DTC code. Understanding the potential causes is vital for effective diagnosis and repair. Here are a few common triggers:

  1. Faulty Transmission Fluid Pressure Sensor: A malfunctioning or damaged transmission fluid pressure sensor is a typical cause of the P1844 code. Over time, these sensors can wear out or become contaminated, hindering accurate pressure readings.

  2. Wiring Issues: Damaged, frayed, or corroded wires and connectors in the transmission pressure sensor circuit can disrupt the proper transmission fluid pressure signal. This can trigger the P1844 code and negatively affect transmission performance.

  3. Transmission Fluid Problems: Insufficient or contaminated transmission fluid can lead to improper pressure readings. Low fluid levels or fluid that has degraded over time due to lack of maintenance may contribute to the P1844 code.

Symptoms of the P1844 DTC Code

Detecting the symptoms associated with the P1844 code can aid in prompt diagnosis and mitigation. Common symptoms include:

  • Illuminated Check Engine Light: The most noticeable symptom is the illumination of the vehicle’s Check Engine Light. The PCM detects the fault and triggers the P1844 code, prompting the warning light to appear on the dashboard.

  • Transmission Issues: The vehicle may experience transmission-related issues such as harsh shifting, delayed engagement, or slipping gears. In severe cases, the vehicle might even go into a “limp mode” where it remains stuck in a single gear.

  • Reduced Fuel Efficiency: A malfunctioning transmission system can cause an increase in fuel consumption. If you notice a significant drop in your vehicle’s fuel efficiency, it could be due to the P1844 code.

Diagnosis of the P1844 DTC Code

Once the P1844 code is detected, a thorough diagnosis is necessary to identify the root cause accurately. Here are the steps involved:

  1. OBD-II Scanner: Begin by using an OBD-II scanner to retrieve the specific trouble code. This will indicate the presence of the P1844 code and provide valuable insights into the issue.

  2. Visual Inspection: Perform a visual inspection of the transmission system, paying close attention to the wiring, connectors, and transmission fluid levels. Look for any signs of damage, corrosion, or leaks.

  3. Check Transmission Fluid Pressure: Utilize a pressure gauge to measure the transmission fluid pressure. Compare the obtained readings with the manufacturer’s specifications to identify any anomalies.

  4. Conduct Resistance Tests: Test the resistance across the transmission fluid pressure sensor circuit using a multimeter. Compare the results with the acceptable range specified by the manufacturer.

Potential Solutions for the P1844 DTC Code

Addressing the P1844 code promptly is crucial to prevent further damage and ensure optimal vehicle performance. Here are some potential solutions for resolving the issue:

  1. Replace Faulty Sensor: If the transmission fluid pressure sensor is determined to be faulty, replace it with a new, OEM-quality sensor. Ensure the new sensor is compatible with your vehicle’s make and model.

  2. Repair Wiring Issues: If damaged or corroded wiring is identified during the visual inspection, repair or replace the affected wires and connectors. Ensure all connections are secure and free from any excessive resistance.

  3. Check and Replace Transmission Fluid: Inspect the transmission fluid for proper levels and quality. Low levels or contaminated fluid must be addressed immediately. Drain and replace the fluid following the manufacturer’s guidelines.

Frequently Asked Questions about the P1844 DTC Code

  1. Q: Can I continue driving my vehicle with the P1844 DTC code present? A: It is not recommended to drive your vehicle with the P1844 code. Continuing to drive may exacerbate the existing issues, leading to further transmission damage. Seek professional assistance to diagnose and resolve the problem.

  2. Q: How much does it cost to fix the P1844 DTC code? A: The cost of resolving the P1844 code can vary depending on factors such as the vehicle’s make and model, the extent of the damage, and the labor rates of the repair facility. It is best to consult a qualified mechanic or dealership for an accurate estimate.

  3. Q: Can I clear the P1844 code without fixing the underlying issue? A: While clearing the code might temporarily remove the check engine light, it does not address the root cause of the problem. If left unaddressed, the underlying issue can worsen over time, potentially leading to more expensive repairs. It is recommended to diagnose and fix the problem to ensure the vehicle operates optimally.


The P1844 DTC code indicates a malfunction in the transmission fluid pressure sensor or switch circuit. Prompt diagnosis and appropriate repairs are essential to maintain vehicle performance and prevent further damage. By understanding the causes, symptoms, diagnosis, and potential solutions outlined in this guide, you can effectively address the P1844 code and get your vehicle back on the road with optimal transmission functioning.

About author


Meet Sam Mitchell, your experienced and reliable guide in the complex world of car fault codes. With a robust career spanning over 15 years as a professional car mechanic, John has the skills, knowledge, and practical experience to help you navigate car fault issues with confidence.


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