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Failed Smog Test

OBD Trouble Code P0741 Torque Converter Clutch Circuit Problem

Car has less than 50k miles on it and it failed the smog check because the check engine light was on. The smog tech said he got a trouble code P0741... something to do with the transmission torque converter clutch. P0741 torque converter clutch circuit performance of stuck off - What does this mean? Please translate... thank you!


OBD-II P0741 Trouble Code

Torque Converter Clutch Circuit Performance or Stuck Off

Here is what a P0741 means, in simple terms

P0741 is an OBD-II generic code. A P0741 is set whenever an engine's control computer (ECC) detects a fault with the vehicle's transmission torque converter clutch. The transmission torque converter clutch is designed to lock the torque converter when the vehicle is in high speed. When the ECC notices a difference greater than 200 revolutions per minute between the rotation speed of the torque converter and the rotation speed of the transmission input shaft, the computer triggers a P0741 diagnostic trouble code. The rotational speed of the torque converter and the input transmission shaft should be equal when the torque converter lockup engages.

What caused my vehicle to set a P0741 trouble code?

There a several components which make up the torque converter clutch system. We'll start with the main component which is torque converter clutch. The transmission torque converter clutch is designed to lock the torque converter when the vehicle is in high speed. The second component is the transmission valve body, which on most vehicles holds the torque converter clutch (TTC) solenoid. On certain vehicle's the TTC solenoid is positioned seperate from the valve body. The TCC solinoid is controled by the ECC and used to engage the torque converter clutch. Common P0741 trouble code reasons include:

  • Faulty torque converter clutch
  • Faulty torque converter solenoid
  • Restricted transmission fluid passages inside transmission
  • Internal electrical fault with the TCC solenoid
  • Internal mechanical fault with the TCC solenoid
  • Defective valve body (contains multiple solenoid, including the TCC solenoid)
  • Defective Transmission Control Module (TCM)
  • Defective Engine Coolant Temperature (ECT) sensor. This is a rare fault which causes a P0741.
  • Damaged transmission wiring and/or wiring harness

What symptoms will my vehicle experience when trouble code P0741 is set?

  • Your vehicle check engine light (CEL), Malfunction Indicator Lamp (MIL) or Service Engine Soon light will be illuminated and freeze frame data stored with information regarding engine sensor data at the time when the ECC detected the transmission torque converter clutch problem. Trouble code P0741 will also be recorded in the ECC ROM memory.
  • Bad fuel economy.
  • Unable to drive at high speed.
  • Transmission not shifting to high gears.

How can I fix a P0741 problem and where should I start?

We first recommend pulling the trouble code(s) from the ECC, along with the freeze frame data. The freeze frame data will give you information on the engine's exact operating condition at the precise moment the trouble code was triggered. Write down or record this information somewhere. Next, clear the ECC and drive your vehicle for at least 200 miles or until the check engine light turns on again. Try and re-create the engine condition using the freeze frame data. If the check engine light returns, extract the trouble codes and verify that trouble code P0741 is present. If so, move on to inspecting the transmission fuse(s). Ensure none are defective. Next move on to checking the wiring harness and wiring connections to the transmission for damaged. If the wiring to the transmission control module and torque converter clutch solenoid are not damaged, your next step would be to test the TCC solenoid itself, as well as verify the TCM is commanding the solenoid on (power at solenoid when activated by TCM). This diagnosis is a bit more complicated and may require an experienced technician. Possible fixes to clear a OBD-II Trouble Code P0741 include:
  • Replace the TCC solenoid
  • Repair TCC solenoid wiring
  • Replace valve body, including all solenoids
  • Replace transmission control module.
  • Repair damaged transmission wiring harness/connector
  • Replace defective engine coolant temperature sensor
  • Replace torque converter clutch

Can I drive my vehicle with a P0741 trouble code and illuminated CEL?

  • You may drive your vehicle with a P0741 however keep in mind your vehicle will not pass a smog inspection.
  • Problems with the torque converter clutch operation may cause drive-ability symptoms.
  • The check engine light or malfunction indicator lamp will be illuminated as long as a P0741 is recorded in the ECC.

posted by SmogTips Support 10-10-2017 01:42 PM
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