Transmission Fluid Pressure Sensor/Switch Circuit High
The P0873 code indicates that the Powertrain Control Module (PCM) has detected a voltage signal from the transmission fluid pressure sensor that is higher than the expected range. This sensor monitors hydraulic pressure inside the transmission to ensure proper shift timing and line pressure. A high circuit condition typically means the sensor is sending an abnormally high voltage, often due to a short to power, internal sensor failure, or wiring issues. This can lead to harsh shifts, slipping, or limp mode.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission slipping or delayed engagement
- Vehicle may enter limp mode
2. Most Common Causes
- Faulty transmission fluid pressure sensor
- Short to power in the sensor circuit wiring
- Damaged connector or corroded terminals
- Internal transmission problem causing high pressure
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the sensor and wiring for damage, corrosion, or loose connections.
Step 3: Using a multimeter, check the sensor signal voltage at idle and compare to manufacturer specifications (typically 0.5-4.5V).
Step 4: If voltage is high (e.g., 5V), disconnect the sensor; if voltage drops, replace the sensor. If voltage remains high, repair the short to power in the wiring.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a high circuit condition can cause harsh shifts, transmission damage, or unexpected limp mode, which may be dangerous.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and sensor replacement, but can be higher if wiring repairs or transmission work is needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.