P0843 Fault Code

Transmission Fluid Pressure Sensor/Switch A Circuit High

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0843 fault code indicates an issue with the Transmission Fluid Pressure Sensor or Switch A Circuit, specifically that it has registered a high voltage. This component is crucial for the engine control unit (ECU) to adjust the transmission shifting based on the pressure of the fluid. When the signal from this sensor is high, it may lead to improper shifting and other transmission-related issues.

What are the symptoms of the P0843 code?

Drivers may experience various symptoms when the P0843 code is present, such as:

• Erratic or harsh shifting between gears
• Slipping of the transmission
• Delayed engagement or response when shifting
• Illumination of the Check Engine Light (CEL)
• Possible overheating of the transmission fluid.

What causes the P0843 code?

Common causes of the P0843 code can include:

• Faulty transmission fluid pressure sensor
• Worn or damaged wiring or connectors in the sensor circuit
• Low transmission fluid levels, which might alter pressure readings
• Short circuits or electrical issues in the transmission control module (TCM)
• Internal transmission failure affecting fluid pressure sensors.

How to fix P0843?

To resolve the P0843 code, follow these steps:

• Perform a diagnostic check to confirm the code and assess other potential trouble codes.
• Inspect the wiring and connectors for any signs of wear, corrosion, or damage. Repair or replace as necessary.
• Check the transmission fluid level and quality; top off or change the fluid if it is low or contaminated.
• Test the transmission fluid pressure sensor for proper functionality using a multimeter; replace if faulty.
• If all components seem fine, further inspection of the transmission may be needed to assess for internal issues.