P0873 Technical Description
Transmission Fluid Pressure Sensor/Switch “C” Circuit High
If you’re staring at a P0873 trouble code on your dashboard, you’re probably looking for some clear answers and a reliable fix.
This guide covers the essentials: what the code means, symptoms, causes, and step-by-step solutions.
Having dealt with this error in several high-mileage transmissions, I know the frustration and the fixes well.
In this article, we’ll delve specifically into the common causes of the P0873 code and effective troubleshooting steps to address it, ensuring your vehicle returns to peak performance.
Time to roll up our sleeves and get into the details.
Key Takeaways
- Understanding P0873: This code indicates a problem with the “C” pressure sensor/switch in your transmission, signaling high fluid pressure.
- Symptoms to Watch: Symptoms include transmission slipping, harsh shifts, overheating, reduced fuel efficiency, warning lights, unusual noises, and potential stalling.
- Common Causes: Causes range from faulty sensors, improper fluid levels, blocked passages, damaged wiring, to internal mechanical wear.
- Diagnostic Steps: Start by checking the transmission fluid, inspecting the sensor and wiring, and scanning for additional codes.
- Fixing the Issue: Repair may involve adjusting fluid levels, replacing the sensor, clearing blocked passages, or more complex internal repairs.
- Seeking Help: If the problem persists or the repairs are beyond your skill level, consulting with a professional mechanic is advised.
Table of ContentsShow
What Does P0873 Trouble Code Mean?
When your vehicle’s diagnostic system flashes a P0873 trouble code, it’s signaling an issue with the “C” pressure sensor/switch in your transmission.
Specifically, this code is indicative of the sensor output being higher than normal, suggesting that the transmission fluid pressure is either too high or the sensor itself is malfunctioning.
Here’s what’s really happening:
Your car’s transmission relies on fluid to operate smoothly by lubricating moving parts, cooling the transmission, and facilitating gear shifts.
The pressure sensors, like the one indicated by the “C” in this trouble code, monitor the fluid’s pressure to ensure it’s within the manufacturer’s specified range. This monitoring is crucial for the transmission’s efficiency and longevity.
A P0873 code pops up when the sensor detects pressure that exceeds the upper limits. This could be due to actual high fluid pressure or a fault in the sensor or its circuit.
High fluid pressure in a transmission can force other components to work harder, which may lead to premature wear or failure. Conversely, a faulty sensor might incorrectly report high pressure when in reality, everything is normal.
Understanding this trouble code is key to preventing further damage to your vehicle. It alerts you to check whether there’s a genuine pressure issue or if the sensor is just crying wolf. Ignoring this warning could lead to significant transmission damage, which is expensive to repair.
In sum, a P0873 code isn’t just a random set of characters; it’s a critical signal from your vehicle that something is wrong.
It’s essential to investigate whether you’re dealing with an actual pressure problem or just a faulty sensor so you can address the issue promptly and maintain your vehicle’s health.
P0873 Trouble Code Symptoms
If your car is showing a P0873 trouble code, you might notice several warning signs. Here are the key symptoms to watch for:
- Transmission Slipping: The car may feel like it’s shifting gears unpredictably or not staying in gear.
- Harsh Gear Shifts: You might experience jolts or unusually hard shifts between gears.
- Overheating Transmission: The transmission may overheat, which can lead to further mechanical issues if not addressed.
- Decreased Fuel Efficiency: Inefficient gear transitions can reduce your vehicle’s miles per gallon.
- Warning Light: The check engine or transmission warning light will illuminate on your dashboard.
- Unusual Noises: Listen for strange sounds from the transmission area, indicating mechanical distress.
- Vehicle Stalling: The car may stall due to improper transmission fluid pressure.
P0873 Trouble Code Causes
The P0873 trouble code can be triggered by a variety of issues related to the transmission fluid pressure. Here are the common causes:
- Faulty Pressure Sensor: The sensor may be malfunctioning and sending incorrect signals.
- High Transmission Fluid Level: Excessive fluid can cause higher than normal pressure readings.
- Low Transmission Fluid Level: Conversely, too little fluid can also disrupt pressure levels and lead to faulty sensor readings.
- Blocked Fluid Passage: Obstructions in the fluid’s pathway can increase pressure unnaturally.
- Damaged Wiring or Connectors: Any damage to the sensor’s electrical system can result in inaccurate readings.
- Transmission Fluid Contamination: Dirty or unsuitable fluid can cause incorrect pressure readings and damage components.
- Mechanical Transmission Damage: Internal wear or damage in the transmission can alter pressure dynamics.
How To Fix A P0873 Trouble Code
Resolving a P0873 trouble code involves several diagnostic and repair steps to pinpoint and correct the issue with the transmission fluid pressure sensor. Here’s a step-by-step guide on how to tackle this problem:
1. Check Transmission Fluid Levels
Begin by checking the transmission fluid level and its condition. The fluid should be at the manufacturer’s recommended level and clean, not burnt or gritty. Adjust the fluid level or replace the fluid if needed.
2. Inspect the Pressure Sensor and Circuit
Examine the pressure sensor itself for any signs of damage or corrosion. Also, check the wiring and connectors leading to the sensor. Look for frayed wires, loose connections, or any signs of corrosion. Replace or repair any faulty components.
3. Scan for Additional Codes
Use an OBD-II scanner to check for other related diagnostic trouble codes. Multiple codes could indicate a more complex issue with the transmission system.
4. Test the Sensor
If the sensor and wiring appear intact, test the sensor’s functionality with a multimeter. Compare your findings to the specifications in your vehicle’s service manual. Replace the sensor if it does not meet specifications.
5. Inspect Transmission Internally
If the sensor and fluid levels are correct, and there are no wiring issues, a more in-depth examination of the transmission may be necessary. This could involve inspecting for blocked passages or mechanical wear inside the transmission.
6. Clear the Code and Road Test
After repairs, clear the trouble code from your vehicle’s computer with an OBD-II scanner and take your vehicle for a test drive to ensure that the code does not reappear and the symptoms are resolved.
Addressing a P0873 can be straightforward if it’s a sensor or fluid issue but may require more extensive repairs if related to internal transmission damage. Always consider consulting with a professional mechanic if the problem persists or if you are not comfortable performing these diagnostics and repairs yourself.
Conclusion
Now that you’ve got the scoop on what the P0873 trouble code means and the steps to fix it, you’re well-prepared to tackle the issue head-on.
Have you encountered this trouble code before? What was your experience?
Drop a comment below and share how these tips worked out for you or any other insights you have on handling transmission issues!
