U0731 - Communication Error with Hybrid Powertrain Control Module (HPCM) - Common in 2015-2019 Chevrolet Volt

Quick Answer

U0731 means: DTC U0731 means there's a communication problem between the Engine Control Module and Hybrid Powertrain Control Module.

Fix: Check and replace faulty components Cost: $150 - $300 Time: 90-180 minutes

Can I drive with U0731? Immediate attention is recommended to avoid further damage.

Common Questions

What does U0731 mean and how does it affect my car?

DTC U0731 indicates a communication error between your car's Engine Control Module and the Hybrid Powertrain Control Module. This can lead to poor engine performance, reduced power, and even starting issues. If this code appears, your vehicle may struggle to accelerate or maintain speed, affecting your safety on the road.

What are the most common causes of U0731 and how much does it cost to fix?

Common causes of U0731 include faulty wiring between the ECM and HPCM, with repair costs ranging from $150 to $300. A failed HPCM can cost between $800 and $1,200 to replace. Regular maintenance and inspection can help prevent these issues.

Can I drive my car with U0731 or should I stop immediately?

It is not advisable to drive your vehicle with a U0731 code as it can lead to significant performance issues and even a complete breakdown. It is best to have the vehicle inspected by a professional as soon as possible.

How can I diagnose U0731 myself using GeekOBD APP?

To diagnose U0731, you can use the GeekOBD APP to scan your vehicle's OBD2 system. Look for the U0731 code and any other related codes. Check the freeze frame data for conditions at the time of the fault, and use the app's live data feature to monitor the performance of the ECM and HPCM.

What vehicles are most commonly affected by U0731?

DTC U0731 is commonly found in hybrid vehicles, especially the Chevrolet Volt models from 2015 to 2019. Other hybrid models may also experience this issue, so it's important to consult your vehicle's specific repair manual.

How can I prevent U0731 from happening again?

To prevent U0731, ensure regular maintenance is performed on your vehicle. This includes checking and cleaning electrical connections, monitoring battery health, and ensuring that software updates for the ECM and HPCM are applied as required.

What is U0731?

DTC U0731 is a diagnostic trouble code that indicates a communication error between the Engine Control Module (ECM) and the Hybrid Powertrain Control Module (HPCM). This code often arises in hybrid vehicles, particularly in models like the 2015-2019 Chevrolet Volt. When this code is triggered, it suggests that the ECM is unable to communicate effectively with the HPCM, which is crucial for the vehicle's operation. This communication failure can lead to various performance issues, such as reduced power, erratic engine behavior, and even difficulties with starting the vehicle. The implications of this code are significant, as it can affect the vehicle's fuel efficiency and overall drivability. If you see this code, it’s important to address it promptly to prevent further damage to the vehicle's hybrid system or other engine components. Ignoring DTC U0731 can lead to more costly repairs down the line, as prolonged communication issues can cause strain on the electrical systems and sensors involved. Overall, understanding this code is essential for maintaining optimal vehicle performance and ensuring a safe driving experience.

System: U - Network (Communication, CAN Bus)

Symptoms

Common symptoms when U0731 is present:

  • The check engine light is illuminated continuously, indicating a persistent issue that needs attention.
  • The vehicle experiences reduced power during acceleration, making it difficult to merge into traffic safely.
  • Fuel economy may decrease by 15-20%, leading to higher fuel costs over time.
  • Erratic engine behavior, such as stalling or unexpected engine shutdowns, may occur during operation.
  • The vehicle may fail to start altogether, causing significant inconvenience.

Possible Causes

Most common causes of U0731 (ordered by frequency):

  1. The most common cause of U0731 is a faulty wiring harness that connects the ECM and HPCM, with a likelihood of around 60%. Corrosion or damage can disrupt communication.
  2. Another frequent cause is a failed HPCM itself, which may not send or receive signals properly, accounting for about 25% of cases.
  3. Poor battery connections or a weak 12V battery can also trigger this code, affecting the power supply to the modules involved. Regular battery maintenance can help prevent this.
  4. Less common causes include software issues within the ECM or HPCM that require reprogramming or updates to resolve.
  5. In rare cases, a complete ECM failure may occur, which is serious and requires immediate professional diagnosis.

U0731 Repair Costs

Cost Breakdown by Repair Type

Wiring Harness Repair

Repair or replacement of damaged wiring harness between ECM and HPCM.

  • Total: $150 - $300
  • Success rate: 85%
HPCM Replacement

Replacement of the Hybrid Powertrain Control Module if found faulty.

  • Total: $800 - $1,200
  • Success rate: 90%
ECM Reprogramming

Reprogramming the Engine Control Module software.

  • Total: $100 - $200
  • Success rate: 70%
Money-Saving Tips for U0731
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional U0731 Diagnosis Process

Follow these systematic steps to accurately diagnose U0731. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Perform an initial visual inspection to check for damaged wiring, loose connections, or corrosion around the ECM and HPCM - this should take about 5-10 minutes

Step 1: Perform an initial visual inspection to check for damaged wiring, loose connections, or corrosion around the ECM and HPCM - this should take about 5-10 minutes.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: Use an OBD2 scanner, such as the GeekOBD APP, to retrieve all stored codes and freeze frame data, helping you understand the fault context and any additional codes present - this may take 10-15 minutes

Step 2: Use an OBD2 scanner, such as the GeekOBD APP, to retrieve all stored codes and freeze frame data, helping you understand the fault context and any additional codes present - this may take 10-15 minutes.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Conduct component testing with a multimeter to check the voltage and resistance of the affected modules, which can take around 20-30 minutes depending on findings

Step 3: Conduct component testing with a multimeter to check the voltage and resistance of the affected modules, which can take around 20-30 minutes depending on findings.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: After any repairs, perform a system function test to ensure that the modules are communicating correctly, which should take about 10-15 minutes

Step 4: After any repairs, perform a system function test to ensure that the modules are communicating correctly, which should take about 10-15 minutes.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Finally, conduct a road test to verify that the vehicle operates normally under various conditions, confirming that the issue has been resolved

Step 5: Finally, conduct a road test to verify that the vehicle operates normally under various conditions, confirming that the issue has been resolved. This may take 15-20 minutes.

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: Chevrolet Volt Communication Issue

Vehicle: 2016 Chevrolet Volt, 45,000 miles

Problem: Customer reported a persistent check engine light and reduced engine power.

Diagnosis: After performing a visual inspection and running an OBD2 scan, DTC U0731 was confirmed. Further inspection revealed corroded wiring.

Solution: Repaired the wiring harness and cleared the codes. The vehicle was then road tested successfully.

Cost: $250 for repairs and diagnostic fees.

Result: The check engine light remained off, and the vehicle's performance returned to normal.

Case Study 2: Failed HPCM Replacement

Vehicle: 2018 Chevrolet Volt, 30,000 miles

Problem: Customer experienced starting issues and intermittent stalling.

Diagnosis: DTC U0731 was retrieved, and testing confirmed a faulty HPCM that failed to communicate with the ECM.

Solution: Replaced the HPCM and reprogrammed the ECM to restore communication.

Cost: $1,000 for parts and labor.

Result: The vehicle started reliably, and no further issues were reported post-repair.

Diagnose U0731

Use GeekOBD APP for professional diagnosis!

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Code Information

Code: U0731
System: Network (Communication, CAN Bus)
Severity: HIGH
Category: Network Codes