P0803 - 1-4 Upshift Solenoid Control Circuit Malfunction
The P0803 code indicates a malfunction in the control circuit of the 1-4 upshift solenoid, also known as the skip shift solenoid. This solenoid is part of the Computer Aided Gear Selection (CAGS) system found in some manual transmission vehicles, typically Chevrolet Corvettes and Camaros. The system forces a shift from 1st to 4th gear under light throttle to improve fuel economy. When the PCM detects an open, short, or excessive resistance in the solenoid circuit, it sets this code.
01. Most Common Causes
- Faulty 1-4 upshift solenoid
- Open or shorted wiring in the solenoid circuit
- Poor electrical connection at the solenoid or PCM
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Inability to shift from 1st to 2nd gear (stuck in 1st or forced 4th)
- Harsh or erratic shifting
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the solenoid and wiring for damage or corrosion.
Step 3: Test the solenoid resistance with a multimeter (specs: 20-30 ohms).
Step 4: Check for voltage and ground at the solenoid connector with the ignition on.
Step 5: If wiring and solenoid are good, test the PCM output or replace the PCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but the skip shift feature may be disabled, and you may experience abnormal shifting. It is safe for short trips, but repair is recommended to avoid transmission damage.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor, depending on whether the solenoid or wiring needs replacement.