Transmission Fluid Pressure Sensor/Switch Circuit Malfunction
The P0845 code indicates a problem in the transmission fluid pressure sensor or its circuit. This sensor monitors hydraulic pressure inside the transmission and sends a signal to the powertrain control module (PCM) to adjust shift patterns. A fault can cause incorrect pressure readings, leading to harsh shifting, slipping, or limp mode.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission slipping or delayed engagement
- Transmission stuck in limp mode
2. Most Common Causes
- Faulty transmission fluid pressure sensor/switch 'B'
- Open or short circuit in the signal, 5V reference, or ground wiring
- Corroded, loose, or damaged connector terminals
- Low transmission fluid level or contaminated/burnt fluid
- Internal transmission mechanical failure (valves, valve body, pump)
- Defective transmission control module (TCM/PCM)
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition; top off or replace if necessary.
Step 3: Visually check sensor wiring and connectors for damage or corrosion.
Step 4: Test sensor resistance and voltage with a multimeter per manufacturer specs.
Step 5: If sensor and wiring are OK, suspect internal transmission issue; perform pressure test.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0845 can cause transmission damage due to improper pressure regulation. You may experience harsh shifting or slipping, which can worsen internal wear.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for sensor replacement and diagnosis. If internal transmission damage is found, repairs can exceed $1,000.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.