Quick Answer
P0956 means: P0956 indicates a performance issue with the Transmission Control Module (TCM).
Can I drive with P0956? Immediate attention is recommended to prevent further transmission damage.
Common Questions
What does P0956 mean and how does it affect my car?
P0956 indicates that the Transmission Control Module (TCM) is experiencing performance issues. This can lead to noticeable changes in how your vehicle shifts gears, potentially resulting in delays, rough shifts, or even failure to shift at all. Long-term neglect of this issue may cause further damage to your transmission, leading to costly repairs.
What are the most common causes of P0956 and how much does it cost to fix?
Common causes of P0956 include a faulty TCM, wiring issues, or low transmission fluid. Repair costs can range from $100 for simple wiring repairs to $1500 for a complete TCM replacement, depending on the nature of the problem.
Can I drive my car with P0956 or should I stop immediately?
While it might be possible to drive your vehicle short distances with the P0956 code, it is not advisable. Continuing to drive can exacerbate transmission issues, leading to more severe damage. It's best to have the vehicle inspected as soon as possible.
How can I diagnose P0956 myself using GeekOBD APP?
You can use the GeekOBD APP to retrieve the DTC codes and freeze frame data, which provides context for the fault. Check for additional codes that may help pinpoint the issue, and inspect the transmission fluid level and condition before proceeding with further diagnostics.
What vehicles are most commonly affected by P0956?
The P0956 code is most commonly reported in vehicles like the 2015-2019 Honda Civic and Toyota Corolla. It’s essential to keep an eye out for any manufacturer recalls or Technical Service Bulletins (TSBs) related to transmission issues in these models.
How can I prevent P0956 from happening again?
Regularly check and maintain your transmission fluid levels, and ensure that your vehicle's wiring and connectors are in good condition. Keeping your vehicle serviced according to the manufacturer's schedule can help prevent issues like P0956 from arising.
What is P0956?
The Diagnostic Trouble Code (DTC) P0956 indicates a problem with the Transmission Control Module (TCM) performance, particularly in vehicles such as the Honda Civic and Toyota Corolla, manufactured between 2015-2019. This code signifies that the TCM is not functioning as expected, which can lead to various transmission issues. The TCM is responsible for managing automatic transmission operations, including gear shifts and performance. When it detects a fault, it triggers the Check Engine Light (CEL) and stores the P0956 code. Real-world implications of this code can range from decreased fuel efficiency to a complete failure of the vehicle to shift gears, significantly impacting drivability. Ignoring this code could lead to more severe transmission problems over time, which can be costly to repair. Additionally, a malfunctioning TCM can affect how smoothly your vehicle accelerates and decelerates, resulting in a less enjoyable driving experience. If you encounter this code, it’s crucial to address it promptly to avoid further damage to the transmission system.
System: P - Powertrain (Engine, Transmission, Emissions)
Symptoms
Common symptoms when P0956 is present:
- Check engine light stays on constantly, indicating a persistent issue with the transmission control module.
- Engine hesitates during acceleration, leading to a frustrating driving experience and potential safety concerns.
- Fuel economy decreased by 10-15%, resulting in higher fuel costs due to inefficient transmission performance.
- Shifting delays or harsh shifts when changing gears, which may lead to noticeable jerking or slipping.
- Unusual noises during shifting, such as grinding or whining, that can indicate serious transmission issues.
Possible Causes
Most common causes of P0956 (ordered by frequency):
- The most common cause of P0956 is a faulty Transmission Control Module, which occurs in about 60% of cases. This can be due to software issues or internal component failures.
- A second common cause is wiring problems, which can include damaged or corroded wiring harnesses that affect communication between the TCM and other components.
- The third cause is low transmission fluid levels, which can lead to overheating and performance issues. Regularly checking and maintaining fluid levels can help prevent this.
- A less common but serious cause is a failing transmission solenoid, which can disrupt the gear shifting process and lead to significant transmission damage if not addressed.
- In rare cases, a software glitch in the TCM could trigger this code, requiring an update or reprogramming to resolve.
P0956 Repair Costs
Cost Breakdown by Repair Type
Transmission Control Module Replacement
Replacing the faulty TCM with a new unit, including reprogramming.
- Total: $800 - $1500
- Success rate: 85%
Wiring Repair
Fixing damaged wiring harness or connections, if applicable.
- Total: $100 - $400
- Success rate: 70%
Money-Saving Tips for P0956
- 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 P0956 Diagnosis Process
Follow these systematic steps to accurately diagnose P0956. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)
Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes).
Step 2: Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)
Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes).
Step 3: Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components like the TCM and wiring (20-30 minutes)
Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components like the TCM and wiring (20-30 minutes).
Step 4: Step 4: System function test - Verify proper operation after repairs and clear codes using the GeekOBD APP (10-15 minutes)
Step 4: System function test - Verify proper operation after repairs and clear codes using the GeekOBD APP (10-15 minutes).
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success (15-20 minutes)
Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success (15-20 minutes).
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: Honda Civic TCM Replacement
Vehicle: 2017 Honda Civic, 45,000 miles
Problem: Customer reported a check engine light and rough shifting.
Diagnosis: After scanning for codes, P0956 was identified. A visual inspection revealed corroded wiring to the TCM.
Solution: Replaced the damaged wiring and reprogrammed the TCM.
Cost: $1200 (parts: $700 for TCM, $500 for labor)
Result: The vehicle shifted smoothly after repair, and the check engine light was cleared.
Case Study 2: Toyota Corolla Wiring Repair
Vehicle: 2018 Toyota Corolla, 30,000 miles
Problem: Customer noticed a delay in shifting and CEL on.
Diagnosis: P0956 was confirmed after scanning. Wiring harness showed signs of wear.
Solution: Repaired the damaged wiring connections.
Cost: $250 (parts: $50 for wiring, $200 for labor)
Result: The shifting issue was resolved, and the CEL did not return.