WHAT IS OBD-II CODE P0874 – TRANSMISSION FLUID PRESSURE SENSOR/SWITCH C CIRCUIT INTERMITTENT
As a mechanic, one of the most important things you need to understand are OBD codes. OBD codes are diagnostic codes that are generated by an onboard computer (the vehicle’s computer) when it detects a problem with the engine, transmission or any other part of the car. One of the most common OBD-II codes that you might encounter is P0874 – Transmission Fluid Pressure Sensor/Switch C Circuit Intermittent. In this article, we will unpack this code, explain what it means and how to fix it.
WHAT DOES OBD-II CODE P0874 MEAN?
P0874 refers to a transmission fluid pressure sensor/switch C circuit that is intermittent. This means that the transmission control module (TCM) has detected an issue with the transmission fluid pressure sensor and/or its circuit. The transmission fluid pressure sensor determines the pressure of the transmission fluid in the transmission, which is an essential input for the transmission control module to operate the transmission properly. When the TCM detects an issue with the transmission fluid pressure sensor, it will trigger the check engine light and store an OBD-II code – P0874.
SYMPTOMS OF OBD-II CODE P0874
If you have a car that has triggered OBD-II code P0874, there are several symptoms that you might experience:
1. Transmission shifting problems – Your transmission may have difficulty shifting between gears. The transmission may also shift more harshly than usual.
2. Slipping transmission – You might notice that your engine is revving, but your car is not accelerating as it should. This is a sign of a slipping transmission.
3. Transmission overheating – If your transmission overheats, the fluid might start to burn, and you will notice a burning smell coming from your transmission. This may cause permanent damage to the transmission.
4. Check engine light – The most obvious symptom of OBD-II code P0874 is the check engine light. The check engine light will illuminate on your dashboard, indicating that there is a problem with your car’s transmission.
WHAT CAUSES OBD-II CODE P0874?
There are several potential causes of OBD-II code P0874. Here are some of the most common:
1. Faulty Transmission Fluid Pressure Sensor – The most common cause of OBD-II code P0874 is a faulty transmission fluid pressure sensor. The sensor may be damaged, or the wiring might be loose, which can cause the TCM to detect intermittent issues with the sensor.
2. Malfunctioning Transmission Control Module – If there is a problem with the transmission control module, it might not be able to receive or interpret the signals from the transmission fluid pressure sensor correctly. This can cause the TCM to trigger OBD-II code P0874.
3. Low Transmission Fluid Level – If the transmission fluid level is low, it can cause pressure issues in the transmission, which can trigger OBD-II code P0874.
4. Wiring Issues – There might be issues with the wiring connections between the transmission fluid pressure sensor and the TCM. If the wiring is damaged, corroded or loose, it can cause intermittent issues with the sensor signal.
HOW TO DIAGNOSE OBD-II CODE P0874?
Diagnosing OBD-II code P0874 requires specialized equipment and expertise. You will need an OBD-II scanner to read the code from the car’s computer. Once you have the code, you will need to inspect the fluid levels and quality in the transmission. You will also need to check the wiring and connections to the transmission fluid pressure sensor and the TCM. The transmission fluid pressure sensor should be tested to see if it is functioning as it should. If necessary, the transmission fluid pressure sensor should be replaced. It is essential to use the manufacturer’s recommended fluid type and capacity when re-filling the transmission fluid.
HOW TO FIX OBD-II CODE P0874?
The best way to repair OBD-II code P0874 depends on the root cause of the issue. Here are some of the most common fixes:
1. Replace the Transmission Fluid Pressure Sensor – If the transmission fluid pressure sensor is faulty, you will need to replace it. This is a relatively straightforward task that involves removing the old sensor and installing a new one.
2. Repair the Wiring – If there are issues with the wiring connections between the transmission fluid pressure sensor and the TCM, you will need to repair or replace the damaged wiring.
3. Service the Transmission – Regular transmission servicing can help prevent OBD-II code P0874 from occurring. This involves flushing and replacing the transmission fluid, replacing the transmission filter, and checking for any other issues in the transmission.
4. Replace the Transmission Control Module – If there is a problem with the transmission control module, you may need to replace it. This is a more complicated and expensive fix, and it should only be done if other fixes have been attempted and have not resolved the issue.
FREQUENTLY ASKED QUESTIONS
1. What does OBD-II code P0874 mean?
OBD-II code P0874 refers to a transmission fluid pressure sensor/switch C circuit that is intermittent. This means that there may be an issue with the transmission fluid pressure sensor and/or its circuit.
2. What are the symptoms of OBD-II code P0874?
The symptoms of OBD-II code P0874 include transmission shifting problems, slipping transmission, transmission overheating, and a check engine light.
3. What causes OBD-II code P0874?
The most common causes of OBD-II code P0874 are a faulty transmission fluid pressure sensor, malfunctioning transmission control module, low transmission fluid level, and wiring issues.
4. How do you diagnose OBD-II code P0874?
Diagnosing OBD-II code P0874 requires specialized equipment and expertise. An OBD-II scanner is required to read the code from the car’s computer, and the fluid levels and quality in the transmission must be inspected. The wiring and connections to the transmission fluid pressure sensor and the TCM should also be checked, and the fluid pressure sensor tested to see if it is functioning as it should.
5. How do you fix OBD-II code P0874?
The best way to repair OBD-II code P0874 depends on the root cause of the issue. Fixes for OBD-II code P0874 include replacing the transmission fluid pressure sensor, repairing the wiring, servicing the transmission, or replacing the transmission control module.
CONCLUSION
OBD-II code P0874 is a common code that can occur in your car’s computer. The key to fixing this issue is to diagnose the root cause correctly and take the necessary steps to repair it. As a mechanic, it is essential to have the right equipment and expertise to diagnose and fix OBD-II codes properly. By understanding the symptoms, causes and diagnostic process for OBD-II code P0874, you can take the necessary steps to keep your car running smoothly and safely.