U0594: Invalid Data from Hybrid Powertrain Control Module
Diagnostic trouble code U0594 indicates that a control module, typically the powertrain control module (PCM/ECM), has received invalid, corrupt, or out-of-range data from the Hybrid Powertrain Control Module (HPCM). This code falls under network communication codes (U0000-U1000) and is specifically related to data exchange failures between modules over the CAN bus. The HPCM manages the hybrid propulsion system, including the interaction between the internal combustion engine, electric motor, high-voltage battery, and energy regeneration system. When the data transmitted by the HPCM does not meet the format, sequence, or expected values of the receiving module, this diagnostic code is set.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Faulty Hybrid Powertrain Control Module (HPCM)
- Interference or damage to the CAN bus wiring (CAN-H and CAN-L lines)
- Abnormal resistance in the communication bus terminals
- Faulty receiving module that misinterprets the data
- Incomplete or corrupted software update in the HPCM
- Ground or power supply issues to the HPCM
- Corrosion or damage to module connectors
3. Symptoms You Will Notice
- Check Engine Light illuminated
- Hybrid system warning light on
- Reduced fuel economy
- Loss of hybrid assist or regenerative braking
- Vehicle may enter limp mode
4. Step-by-Step Diagnosis
Scan all modules for related codes and freeze frame data
Inspect CAN bus wiring and connectors for damage, corrosion, or loose connections
Check HPCM power and ground circuits for proper voltage and continuity
Perform a network communication test to verify data integrity
If wiring is intact, attempt to reprogram or update the HPCM software
If issue persists, replace the HPCM and verify repair
5. Frequently Asked Questions
Is it safe to drive?▼
Driving with code U0594 is not recommended as it can lead to reduced hybrid system performance, potential loss of power, and may leave you stranded. The severity is high, so have the vehicle diagnosed and repaired promptly.
How much does it cost to fix?▼
Repair costs vary widely depending on the root cause. Diagnostic fees range from $100-$200. If the HPCM needs replacement, parts and labor can cost $800-$1,500. Wiring repairs may be $200-$500. Software updates are typically $100-$200.