Transmission Fluid Pressure Sensor Circuit Intermittent
The P0849 code indicates an intermittent fault in the transmission fluid pressure sensor or its circuit. This sensor monitors hydraulic pressure inside the transmission to ensure proper shift timing and line pressure. An intermittent signal can cause erratic shifting, slipping, or limp mode. Common causes include a faulty sensor, damaged wiring, loose connectors, or low transmission fluid.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Erratic or harsh shifting
- Transmission slipping or delayed engagement
- Transmission stuck in limp mode
2. Most Common Causes
- Faulty or internally worn transmission fluid pressure sensor 'B'
- Loose, oxidized, or corroded electrical connections at the sensor connector
- Wiring harness damage from chafing, intermittent short to ground or voltage
- Intermittent TCM/ECM failure (less common)
- Low or degraded transmission fluid causing erratic pressure readings
- Metal debris or contaminants buildup on the sensor
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition.
Step 3: Visually check wiring and connectors for damage or corrosion.
Step 4: Test sensor resistance and voltage with a multimeter.
Step 5: Perform a wiggle test to reproduce intermittent fault.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause transmission damage or sudden failure. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and sensor replacement, but may be higher if wiring repairs are needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.