The P0840 OBD-II code indicates a problem with the Transmission Fluid Pressure Sensor or Switch “A” Circuit. This code is triggered when the engine control module (PCM) or Transmission Control Module (TCM) detects an issue with the hydraulic fluid pressure necessary for proper transmission operation.
What Does the P0840 Code Mean?
The P0840 code signifies that there is a fault in the transmission fluid pressure sensor or switch circuit. This sensor plays a crucial role in monitoring the fluid pressure within the transmission system, allowing the PCM or TCM to manage shifting and engagement of clutches efficiently.
What Causes the P0840 Code?
Several factors can lead to the P0840 code being set, including:
- Transmission fluid level is low
- Transmission fluid pressure sensor failure
- Transmission Control Module (TCM) failure
- Wiring issues or damaged connectors
What Are the Symptoms of the P0840 Code?
When the P0840 code is present, you may experience a variety of symptoms, such as:
- Transmission may not shift properly
- Increased fuel consumption
- Unusual transmission behavior, such as slipping or harsh shifting
How Serious Is the P0840 Code?
The P0840 code is considered urgent. Ignoring this code can lead to severe transmission issues, which may result in extensive damage and costly repairs. It is important to address this code promptly to ensure the safety and reliability of your vehicle.
How to Diagnose the P0840 Code
To diagnose the P0840 code, a mechanic will typically follow these steps:
- Use an OBD-II scanner to confirm the presence of the P0840 code.
- Inspect the transmission fluid level and condition.
- Check wiring and connectors for damage or corrosion.
- Test the transmission fluid pressure sensor for proper operation.
- Examine the TCM for faults or failures.
Common Repairs for the P0840 Code
Repairs for the P0840 code may include:
- Replacing the transmission fluid pressure sensor
- Repairing or replacing damaged wiring or connectors
- Refilling transmission fluid to the correct level
- Replacing the Transmission Control Module (if faulty)
How Much Does It Cost to Fix the P0840 Code?
The cost to repair the P0840 code can vary widely depending on the underlying issue. Typical costs may range from $100 to $800, depending on whether you need a simple fluid refill, a sensor replacement, or a TCM replacement. Always get a detailed estimate before proceeding with repairs.
Can I Fix the P0840 Code Myself?
While some repairs related to the P0840 code, such as checking fluid levels or inspecting wiring, can be done by a knowledgeable DIYer, many issues require professional diagnostic equipment and experience. If you are unsure, it is always best to consult with a qualified mechanic to avoid further damage.
