What this code means

The TCM has raised hydraulic line pressure to maximum to compensate for excessively worn clutch packs or other internal components. The TCM detected shift times exceeding 0.65 seconds too many times. This is a serious transmission code indicating internal wear. Common on GM front-wheel-drive vehicles with the 4T65E transmission.

Symptoms

• Extremely harsh 1-2 and 2-3 shifts (feels like being rear-ended)
• Check Engine Light
• Hard shifting in all gears
• Shuddering between shifts
• Whining noise from transmission
• Transmission slipping before hard shift

Common causes

• Worn clutch packs (most common)
• Faulty pressure control solenoid
• Low transmission fluid
• Blocked valve body
• Worn seals causing pressure loss
• Contaminated transmission fluid

Diagnostic steps

1. Check transmission fluid level and condition
2. Test line pressure
3. Monitor shift times with scan tool
4. Test pressure control solenoid
5. Inspect valve body for wear
6. Check for related solenoid codes

Repair notes

Change transmission fluid and filter first. If code returns, test pressure control solenoid. In many cases, a transmission rebuild is needed due to worn clutches. A TransGo shift kit can extend life by shortening shift times. Common on Impala, Monte Carlo, Grand Prix, Regal, Century, and Venture.

Other Powertrain codes on this vehicle