Transmission Fluid Pressure Sensor/Switch Circuit Low
The P0847 code indicates that the Transmission Control Module (TCM) has detected a low voltage signal from the transmission fluid pressure sensor or switch circuit. This sensor monitors hydraulic pressure inside the transmission to control shift timing and line pressure. A low circuit condition means the voltage reading is below the expected range, which can be caused by a faulty sensor, wiring issues, or low transmission fluid. This can lead to improper shifting, slipping, or transmission damage if ignored.
01. Most Common Causes
- Faulty transmission fluid pressure sensor
- Damaged or corroded wiring/connectors in the sensor circuit
- Low or contaminated transmission fluid
- Internal transmission mechanical failure
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Erratic or harsh shifting
- Transmission slipping or stuck in gear
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Inspect transmission fluid level and condition; top off or replace if necessary.
Step 3: Visually check the sensor wiring and connector for damage, corrosion, or loose connections.
Step 4: Test the sensor's voltage and resistance with a multimeter; compare to manufacturer specs.
Step 5: If sensor and wiring are okay, check for internal transmission issues (e.g., clogged filter, worn pump).
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0847 can cause erratic shifting, transmission slipping, and potential internal damage. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost varies: replacing the sensor typically costs $50-$150 for parts and labor. If wiring repairs or transmission service is needed, costs can be higher.