P0733 - Gear 3 Incorrect Ratio
The P0733 code indicates that the powertrain control module (PCM) has detected an incorrect gear ratio when the transmission is commanded to shift into 3rd gear. This typically means the transmission is slipping or not engaging properly, often due to low fluid, worn clutches, or a faulty solenoid. The PCM monitors input and output shaft speeds to verify the gear ratio; if the ratio deviates from the expected value, it sets this code.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifting into 3rd gear
- Transmission slipping (engine revs high without acceleration)
- Vehicle may go into limp mode (stuck in 2nd or 3rd gear)
- Poor fuel economy
2. Most Common Causes
- Worn or failed third gear clutch/friction plates
- Faulty third gear shift solenoid
- Low or degraded transmission fluid
- Faulty input (turbine) or output speed sensor
- Internal mechanical transmission problems (bands, planetary gears, rings)
- Failed TCM or ECM
- Damaged wiring, connectors, or corrosion in the transmission circuit
3. Step-by-Step Diagnosis
Step 1: Check transmission fluid level and condition; top off or replace if low or burnt.
Step 2: Scan for additional codes (e.g., P0730, P0740) and inspect wiring/connectors to transmission.
Step 3: Perform a transmission pressure test to check for hydraulic issues.
Step 4: Test shift solenoids and valve body operation; replace if faulty.
Step 5: If internal failure is suspected, remove transmission pan and inspect for debris; may require transmission rebuild or replacement.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a slipping transmission can cause further damage and lead to complete transmission failure. If the vehicle goes into limp mode, you may be able to drive slowly to a repair shop, but avoid highway speeds.
How much does it cost to fix?▼
Costs vary widely. Simple fixes like fluid change or solenoid replacement can be $150-$400. A full transmission rebuild or replacement can range from $1,500 to $4,000 or more.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.