The OBD2 code P0744 is associated with the Torque Converter Clutch (TCC) Circuit Intermittent error, indicating irregular performance in the torque converter’s lock-up mechanism. This code is especially crucial in vehicles with automatic transmissions, as it can lead to noticeable symptoms like surging, shuddering, or difficulty in shifting, which can significantly affect the driving experience and the vehicle’s fuel efficiency.
P0744 quick overview
| Meaning | P0744: Torque Converter Clutch Circuit Intermittent |
| Is it serious? | Yes, it can lead to reduced fuel efficiency, potential transmission damage, and a noticeable impact on drivability. |
| Possible causes | – Incorrect transmission fluid type – Faulty torque converter clutch solenoid – Transmission fluid contamination – Damaged wiring or connectors – Internal transmission mechanical problems |
| How to diagnose? | Check the transmission fluid for level and condition. Inspect wiring and connectors for damage or corrosion. Test the torque converter clutch solenoid and circuit for proper operation. Perform a transmission flush if incorrect or contaminated fluid is suspected. Consult a professional for further diagnostic if the issue persists. |
p0744 Meaning
When your car’s computer throws the P0744 code, it’s telling you there’s something off with the torque converter, a key part that manages how your engine’s power gets to the wheels. Think of it as a bridge between your engine and the wheels that makes sure the car moves smoothly.
If this bridge starts acting up—maybe because of using the wrong transmission fluid, some electrical issues, or internal damage—you might notice your car behaving oddly, like jerking when you try to speed up. It’s a sign that your car needs some attention to avoid bigger problems down the road.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
How to fix P0744 – learn from mechanics
I looked into P0744 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Nissan
Vehicle information 2006 Nissan Murano SL 3.5L CVT
Issue + repair history
- Complaint of Check Engine Light (CEL) on the dash.
- Code P0744 stored in memory.
- After a transmission service, performed by a “friend,” new symptom of bucking and surging on acceleration emerged.
- Wrong fluid used during service, flushed the transmission with the proper fluid.
- Three days later, the code reappeared along with the surge symptom.
Other OBD2 Codes + Test Results
- OBD2 Code: P0744 – Torque Converter Lock Up Error
Mechanic suggestions
- Casey Profitt: Recommends checking with Nissan dealer for warranty coverage; suggests replacement due to transmission’s sensitivity to fluid.
- Al Morris: Suggests trying another flush as a cheap gamble; doubts Nissan will cover warranty due to wrong fluid.
- Adam Barber: Advises CVT replacement; highlights coverage under Nissan CVT Warranty Extension Program, subject to conditions.
- Kenneth Larrison: Suggests transmission replacement as the damage is irreversible; hints at financial responsibility of the “friend” who serviced the transmission.
- William Porter: Recommends checking TSBs for known issues with bucking and surging in Muranos; suggests checking air inlet sealing.
Final fix
- Transmission Valve Body replacement recommended but denied warranty coverage by Nissan; potentially replaced at owner’s expense.
- Post-closure note by Salim Safran suggests a defective TCM might have caused the issue; replaced with a good used one, resolving the problem.
Case #2: Infiniti
Vehicle information 1999 Infiniti I30 3.0L
Issue + repair history
- Initial complaint of P0744 code after several miles of driving.
- Previous replacement of various components including solenoids, converter, and valve body.
- Transmission overhaul with salvage yard valve body, new solenoids, and new converter.
- Concerns about starting in second gear and shuddering during 2-3 shifts.
Other OBD2 Codes + Test Results
- OBD2 Code: P0744 – Torque Converter Lock Up Error
- Shift point test:
- 3-4 @45mph
- 4-4L @50mph
- Line pressure idle:
- D, 2, 1 all = 60psi
- Line pressure @2000rpm:
- D, 2, 1 all = 165 psi
Mechanic suggestions
- Technician 1: Recommends checking the charging system and verifying grounds; shares a similar experience with a bad alternator causing intermittent high voltage output.
- Technician 2: Suggests potential mechanical problems such as a worn valve body, stuck solenoid, or bad converter; asks for further information on line pressure behavior during driving.
- Technician 3: Raises concerns about the condition of solenoids when using a junkyard valve body.
Final fix
- Identified TCC dumping when engaging cruise or using turn signal while TCC was engaged.
- Discovered high resistance in grounds of various components (TCM, cruise module, etc.).
- Cleaned and added grounds to components, improving performance and resolving the issue.
- Post-closure note acknowledges the effectiveness of adding grounds in fixing the problem.
Case #3: Ford
Vehicle information 2008 Ford Fusion SE 2.3L
Issue + repair history
- Initial complaint of no high gear and difficulty starting in park.
- Codes: P0715 (turbine speed sensor circuit), P0744 (TCC Circuit intermittent), P1734, P0791 (intermediate shaft speed sensor).
- Inconsistent starting in park, mostly starts in neutral.
- No reverse initially, but it returns the next day.
- Park/neutral sensor replaced.
- Transmission temperature fluctuates between -40 and 100 degrees in drive, remains stable in reverse.
- Speedometer fluctuates 5-10 MPH on the highway, affecting vehicle speed data.
- Wrench light comes on, transmission doesn’t go into high gear; resetting temporarily resolves the issue.
Other OBD2 Codes + Test Results
- OBD2 Codes: P0374 (gear 4 incorrect ratio)
- Fluid level checked: Good level, dirty fluid
Mechanic suggestions
- Technician 1: Suggests checking scanner for MPH reading as most transmissions rely heavily on speed sense.
- Technician 2: Advises inspecting harness connections to transmission and PCM, highlighting the potential influence of alternator AC output and battery connections on speed sensor codes.
- Technician 3: Recommends checking for wire shorting on brackets, emphasizing potential electrical issues.
Final fix
- Identified water in the connector between the air breather box and battery.
- Dried connector, ensuring good engine starting and proper shifting out of park.
- Post-closure query by Dan Habluetzel about the resolution of the no high gear issue.
How to diagnose P0744
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Explanation |
|---|---|
| Check transmission fluid type and condition | Ensure the correct fluid is used and it’s not contaminated. |
| Inspect wiring and connectors | Look for damage or corrosion that might interrupt electrical flow. |
| Test torque converter clutch solenoid and circuit | Verify the solenoid operates correctly and without interruption. |
| Perform a transmission flush | Replace incorrect or contaminated fluid with the proper type. |
| Consult a professional | Seek expert advice if the problem persists or is complex. |
In the cases reviewed, the P0744 code indicated various underlying issues from incorrect fluid types to electrical problems affecting the torque converter’s operation. Solutions ranged from simple fixes like flushing the transmission and adding proper grounds to more complex repairs or replacements of transmission components. It’s crucial to address this code early to prevent further transmission damage and ensure smooth vehicle operation.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko