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P0843 OBD-II Trouble Code: Transmission Fluid Pressure Sensor A Circuit High

Check Engine Light

P0843 trouble code definition

A P0843 trouble code is related to a vehicle’s automatic transmission and its fluid pressure sensor.

What the P0843 code means

P0843 is an OBD-II generic code for a voltage problem with the transmission fluid pressure sensor in that the signal being sent to the engine control unit is higher than the manufacturer’s parameters for the desired amount of fluid pressure for that given driving condition. This means that the fluid pressure needed to change gears, coast, hold a stopped position, etc. is not what is being read by the sensor.

What causes the P0843 code?

While there could be a number of causes for a P0843, the most common are:

  • Faulty transmission fluid pressure control solenoid
  • Faulty transmission fluid pressure sensor
  • Dirty or contaminated transmission fluid
  • Internal/external transmission line blockages

What are the symptoms of the P0843 code?

Symptoms can range from nothing other than a check engine light, to poor, harsh, and slipped shifting of the transmission. The associated symptoms of a P0843 will help you better determine the root of the problem.

How does a mechanic diagnose the P0843 code?

First, your mechanic will test drive the vehicle to see if there is a noticeable problem with the transmission fluid pressure. This will require getting the transmission fluid up to normal operating temperature too. If there are no adverse conditions, your mechanic will move on to test the pressure sensor with a digital multimeter. The pressure control solenoid will be tested next as well as all associated wiring before determining an internal transmission problem is the culprit.

Common mistakes when diagnosing the P0843 code

Hastily replaced parts may only hide the real problem which could be dirty transmission fluid or internal damage.

How serious is the P0843 code?

The seriousness of a P0843 depends on how the vehicle drives with the code. If operations are as normal, the code could just be a faulty sensor. If not, driving may become difficult.

What repairs can fix the P0843 code?

Additional comments for consideration regarding the P0843 code

When repair a P0843, it’s wise to have the transmission fluid changed and flushed as well. This will help the vehicle’s performance and efficiency.

Need help with a P0843 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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