P0843 Transmission fluid pressure switch sensor "A" circuit high

P0843 – OBD-II Trouble Code Technical Description

Trouble code P0843 indicates the transmission fluid pressure switch sensor "A" circuit is high.

What does the fault code mean P0843?

Trouble code P0843 indicates that the engine control module (PCM) has received a voltage signal from the transmission fluid pressure sensor that is too high. This may indicate problems with the transmission's hydraulic system, which can cause gears to malfunction and other transmission problems. Other trouble codes may also appear along with the P0843 code related to the shift solenoid valve, transmission slippage, lockup, gear ratio, or torque converter lockup clutch.

Possible reasons

Some possible reasons for the P0843 trouble code:

• Transmission fluid pressure sensor malfunction.
• Damage or short circuit in the wires or connectors connecting the pressure sensor to the PCM.
• PCM malfunction caused by internal malfunction or software errors.
• Problems with the transmission hydraulic system, such as clogged or leaking fluid, faulty solenoid valves or torque converter.
• Mechanical damage or wear in the transmission, including the pressure sensor.
• Insufficient or low level of transmission fluid.

What are the symptoms of a fault code? P0843?

Symptoms that may occur with DTC P0843 may include the following:

• Unusual or abnormal changes in automatic transmission operation, such as jerking or hesitation when shifting gears.
• Increased transmission fluid consumption.
• The “Check Engine” light on the instrument panel may illuminate.
• The appearance of other error codes related to transmission operation or transmission fluid pressure.
• Deterioration in overall vehicle performance and handling.

How to diagnose a fault code P0843?

To diagnose DTC P0843, follow these steps:

1. Checking the error code: Use the OBD-II diagnostic scanner to determine the P0843 error code. Write down any additional error codes that may also appear.
2. Visual inspection: Inspect the wires and connectors connecting the transmission fluid pressure sensor to the PCM. Check for damage, corrosion or broken wires.
3. Pressure sensor test: Check the transmission fluid pressure sensor itself for damage or leaks. Make sure it is installed and tightened correctly.
4. Checking the transmission fluid level: Check the level and condition of the transmission fluid. Make sure the fluid level is within the manufacturer's recommendations.
5. Checking the transmission hydraulic system: Check the transmission hydraulic system for blockages, leaks or damage. Pay attention to the condition of the solenoid valves and other components.
6. PCM diagnostics: If all previous steps fail to identify the problem, you may need to diagnose the PCM to check its functionality and whether there are any software errors.

Diagnostic errors

When diagnosing DTC P0843, the following errors may occur:

1. Incomplete diagnosis of pressure sensor: Incorrect or incomplete testing of the transmission fluid pressure sensor itself may lead to incorrect conclusions. It is necessary to carefully check for damage and correct installation.
2. Skipping a visual inspection: Insufficient attention to visual inspection of transmission hydraulic system wires, connectors and components may result in missing key problems such as damaged wires or fluid leaks.
3. Incorrect interpretation of scanner data: Incorrect interpretation of the data received from the diagnostic scanner may lead to an incorrect determination of the cause of the malfunction.
4. Skipping transmission fluid level check: Insufficient attention to the level and condition of the transmission fluid can lead to problems related to its level or quality being ignored.
5. Problems in other systems: Sometimes the cause of the P0843 code can be related to other systems in the vehicle, such as the electrical system or fuel injection system. Failure to diagnose the hydraulic transmission system exclusively can lead to undiagnosed problems in other systems.

It is important to carry out diagnostics carefully and systematically to avoid the above errors and accurately determine the cause of the malfunction.

How serious is the fault code? P0843?

Trouble code P0843 indicates a problem with the transmission fluid pressure sensor. While this code itself is not critical to driving safety, it does indicate potential problems in the transmission hydraulic system that could cause the transmissions to malfunction and otherwise have negative consequences for the vehicle. For example, if the problem remains unresolved, it can lead to further damage to the transmission and more serious problems in the future. Therefore, it is recommended that diagnosis and repair be carried out as soon as possible after this code appears.

What repair will help eliminate the code? P0843?

Troubleshooting trouble code P0843 may include the following steps:

1. Replacing the transmission fluid pressure sensor: If the sensor is identified as the source of the problem, it should be replaced. This usually involves removing the old sensor and installing a new one.
2. Checking Wiring and Connections: Sometimes the error can be caused by damaged or broken wiring or faulty connections. Check the condition of the wires and make sure that all connections are securely fastened.
3. Transmission Hydraulic System Diagnosis: If the problem is not resolved by replacing the sensor, a more detailed transmission hydraulic system diagnosis may be required to identify other problems such as leaks, clogs, or damage.
4. Repair or Replacement of Hydraulic Components: If problems are found with the hydraulic system, appropriate repairs such as replacing gaskets, valves or other components must be performed.
5. Re-Inspection and Testing: After completing the repair work, it is recommended to re-inspect the vehicle and test the transmission system to ensure that the problem is completely resolved and the P0843 code no longer appears.

These steps can be performed at an authorized service center or workshop with experienced transmission repair specialists.

How to Diagnose and Fix P0843 Engine Code - OBD II Trouble Code Explain

P0843 – Brand-specific information

Trouble code P0843 relates to the transmission control system and can be found on various brands of cars, a list of some brands with their meanings:

• Ford - Transmission Fluid Pressure Sensor/Switch A Circuit: High.
• Chevrolet – Transmission fluid pressure sensor/switch “A” circuit high.
• Dodge - Transmission Fluid Pressure Sensor/Switch "A" Circuit: High.
• Toyota – Transmission Fluid Pressure Sensor/Switch “A” Circuit: High Signal.
• Honda – Transmission Fluid Pressure Sensor, Sensor “A” – High Voltage

These transcripts may vary slightly depending on the model and year of the vehicle. It is recommended to use official repair manuals or consult an authorized service center for accurate information about the P0843 code for your specific vehicle make and model.