Intermediate Shaft Speed Sensor C Circuit Malfunction
The P2749 code indicates a problem in the electrical circuit of the intermediate shaft speed sensor 'C', which monitors the rotational speed of the intermediate shaft inside the transmission. This sensor is critical for the transmission control module (TCM) to determine shift timing and torque converter lockup. A fault can cause erratic shifting, limp mode, or transmission damage if ignored.
1. Most Common Causes
- Faulty or worn intermediate shaft speed sensor 'C'
- Damaged, corroded, or high-resistance wiring or connector in the sensor circuit
- Short to ground or voltage in the sensor circuit
- Failed transmission control module (TCM) or related control module
- Mechanical issue with the intermediate shaft or related components affecting sensor reading
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifting
- Transmission stuck in limp mode (e.g., 2nd gear only)
- Speedometer or tachometer erratic readings
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect sensor C wiring and connector for damage, corrosion, or loose pins.
Step 3: Test sensor resistance and voltage supply per manufacturer specs.
Step 4: Check transmission fluid level and condition; top up or replace if necessary.
Step 5: If all else passes, replace intermediate shaft speed sensor C.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P2749 can lead to harsh shifting, transmission overheating, or internal damage. If the transmission enters limp mode, you may lose high gears and risk an accident.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, including parts ($50-$150 for the sensor) and labor ($100-$250). If wiring repair or transmission service is needed, costs may be higher.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.