P0871: Transmission Fluid Pressure Sensor/Switch "C" Circuit Range/Performance

Content

P0871 – OBD-II Trouble Code Technical Description
What does trouble code P0871 mean?
Possible reasons
What are the symptoms of trouble code P0871?
How to diagnose trouble code P0871?
- Diagnostic errors
How serious is trouble code P0871?
What repairs will resolve the P0871 code?
P0871 – Brand Specific Information

P0871 – OBD-II Trouble Code Technical Description

Transmission Fluid Pressure Sensor/Switch "C" Circuit Range/Performance

What does the fault code mean P0871?

The transmission fluid pressure sensor (TFPS) tells the ECU the current pressure inside the transmission. Trouble code P0871 indicates that the sensor signal is abnormal. This code typically applies to OBD-II equipped vehicles such as Jeep, Dodge, Mazda, Nissan, Honda, GM and others. The TFPS is usually located on the side of the valve body inside the transmission, sometimes threaded into the side of the housing. It converts the pressure into an electrical signal for the PCM or TCM. The P0846 code is usually associated with electrical problems, although it can sometimes be caused by mechanical problems in the transmission. Troubleshooting steps vary by manufacturer, TFPS sensor type, and wire color. Associated transmission fluid pressure sensor “C” circuit codes include P0870, P0872, P0873, and P0874.

Possible reasons

The following reasons for setting this code are possible:

Open circuit in the TFPS sensor signal circuit.
Short to voltage in the TFPS sensor signal circuit.
Short circuit to ground in the TFPS sensor signal circuit.
Faulty TFPS sensor.
Problem with internal mechanical transmission.

There may also be the following reasons:

Low transmission fluid level.
Dirty transmission fluid.
Transmission fluid leak.
Overheated transmission.
Overheated engine.
Damaged wiring and connectors.
Failure of the transmission pump.
Transmission fluid pressure sensor malfunction.
Transmission fluid temperature sensor malfunction.
Transmission control module malfunction.
Internal mechanical failure.

What are the symptoms of a fault code? P0871?

The severity depends on the location of the fault in the circuit. The malfunction may result in a change in transmission shifting if it is electronically controlled.

Symptoms of a P0846 code may include:

Fault indicator light
Change the quality of the shift
The car starts off in 2nd or 3rd gear (in “sluggish mode”).

Symptoms of P0871 may include:

Overheating of the transmission
Slip
Failed to engage the gear.

How to diagnose a fault code P0871?

A good start is always to check if there are technical bulletins (TSBs) for your vehicle, as the problem may already be known and have a solution suggested by the manufacturer.

Next, examine the transmission fluid pressure sensor/switch (TFPS) on your vehicle. If external damage is found, such as corrosion or damaged connections, clean them and apply electrical grease to correct the problems.

Next, if the P0846 code returns, you need to check the TFPS and its associated circuits. Check the voltage and resistance of the sensor using a voltmeter and ohmmeter. If the test results are unsatisfactory, replace the TFPS sensor and contact a qualified automotive diagnostician if the problem persists.

When diagnosing a P0871 OBDII code, check the manufacturer's TSB database and inspect the TFPS sensor wiring and connectors for damage. It is also necessary to check the sensor itself to confirm that it is working correctly. If the problem persists, there may be an internal mechanical problem that needs to be looked into further.

Diagnostic errors

Common errors when diagnosing the P0871 trouble code include:

Incomplete check of the manufacturer's TSB database, which may result in missing a known solution to the problem.
Insufficient inspection of the wiring and connectors leading to the TFPS sensor, which may lead to incorrect conclusions about the cause of the malfunction.
Incorrect interpretation of voltage and resistance test results, which may result in unnecessary replacement of the sensor or other components.
Insufficient checking for internal mechanical problems, which can also be the source of the P0871 code.

How serious is the fault code? P0871?

Trouble code P0871 is serious because it indicates a problem with the transmission fluid pressure sensor. This can lead to transmission malfunction, overheating, or other serious vehicle performance problems. It is recommended that the problem be diagnosed and corrected as soon as possible to avoid further damage to the transmission.

What repair will help eliminate the code? P0871?

The following steps are recommended to resolve the P0871 code:

Check and clean connections and wiring leading to the transmission fluid pressure sensor.
Check the condition of the transmission fluid pressure sensor and replace it if necessary.
If internal mechanical problems are found in the valve body or other parts of the transmission, professional intervention is required to repair or replace the damaged parts.
Replace the PCM/TCM as needed if they are indeed the source of the problem.

In case of complex or unclear situations, it is always recommended to contact a qualified technician or mechanic for diagnosis and repair.

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