Pressure Control Solenoid A Intermittent
The P0749 code indicates that the transmission control module (TCM) has detected an intermittent electrical or performance issue with pressure control solenoid A. This solenoid regulates hydraulic pressure within the transmission to control shift timing and firmness. An intermittent fault means the problem comes and goes, often due to wiring issues, connector corrosion, or internal solenoid wear. This can lead to erratic shifting, slipping, or harsh engagement.
1. Symptoms You Will Notice
- Check Engine Light on
- Erratic or harsh shifting
- Transmission slipping or delayed engagement
- Reduced fuel economy
2. Most Common Causes
- Loose, corroded, or damaged connector at the pressure control solenoid
- Intermittent short to ground, short to power, or open circuit in the solenoid wiring
- Internally defective pressure control solenoid 'A' (coil with thermal or mechanical failure)
- Pressure control valve stuck mechanically due to fluid contamination
- Faulty transmission control module (TCM/PCM) with internal solenoid driver failure
- Low transmission fluid level or severely degraded/contaminated fluid
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition; top up or replace if necessary.
Step 3: Visually check wiring and connectors to solenoid A for damage or corrosion.
Step 4: Test solenoid resistance with a multimeter and compare to manufacturer specs.
Step 5: Perform a transmission pressure test to verify solenoid operation.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as intermittent solenoid failure can cause sudden transmission issues, leading to unsafe driving conditions or further damage.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, depending on whether the solenoid is replaced individually or as part of a larger transmission service.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.