Transmission Fluid Pressure Sensor Circuit High
The P0843 code indicates that the Transmission Control Module (TCM) has detected a voltage signal from the transmission fluid pressure (TFP) sensor that is higher than the expected range. This sensor monitors hydraulic pressure within the transmission to ensure proper shift timing and line pressure. A high circuit condition typically points to a short to voltage, faulty sensor, or wiring issues. This can lead to harsh shifts, slipping, or limp mode.
1. Symptoms You Will Notice
- Check Engine Light on
- Harsh or erratic shifting
- Transmission slipping
- Transmission stuck in limp mode
- Reduced fuel economy
2. Most Common Causes
- Faulty transmission fluid pressure sensor
- Short to voltage in sensor circuit
- Damaged wiring or connector
- Corroded terminals
- Internal transmission problem (rare)
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect wiring and connector for damage, corrosion, or shorts.
Step 3: Test sensor voltage and resistance with a multimeter; compare to specs.
Step 4: Check transmission fluid level and condition.
Step 5: If wiring and sensor are good, test TCM and internal circuits.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0843 can cause transmission damage due to improper pressure regulation. You may experience harsh shifts or loss of drive.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Sensor replacement ranges from $100-$300, while wiring repairs may be $50-$200. Total cost depends on labor rates and parts.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.