Output Speed Sensor Circuit Malfunction
The P0720 code indicates a malfunction in the output speed sensor circuit, which monitors the transmission's output shaft speed. This sensor is critical for proper transmission operation, as the PCM uses its signal to control shift timing, torque converter lockup, and line pressure. A failure can cause erratic shifting, limp mode, or transmission damage.
1. Symptoms You Will Notice
- Check Engine Light on
- Erratic or harsh shifting
- Transmission stuck in limp mode
- Speedometer inoperative or erratic
2. Most Common Causes
- Faulty output speed sensor
- Damaged wiring or connector
- Low transmission fluid level
- Internal transmission mechanical failure
3. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0720 is present.
Step 2: Inspect output speed sensor wiring and connector for damage or corrosion.
Step 3: Test sensor resistance and voltage output with a multimeter.
Step 4: Check transmission fluid level and condition.
Step 5: If sensor and wiring are good, inspect for mechanical issues like a damaged tone ring.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0720 can cause harsh shifting, transmission slipping, or sudden failure, potentially leading to costly repairs.
How much does it cost to fix?▼
Replacing the output speed sensor typically costs $50-$150 for parts and labor. If wiring or transmission issues are found, costs can be higher.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.