What Is the P1740 Code?
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Diagnostic code P1740 comes on when your car’s engine control unit (ECU) detects the torque converter clutch (TCC) is not working normally.
The TCC is located between the ECU and TCM and its main role is to optimize performance by controlling transmission fluid temperature and multiplying torque. It is controlled by a solenoid and any problem with the solenoid or the electronic circuit connecting to the engine and transmission will result in the logging of code P1740.
In normal circumstances, all three parts need to be in good working condition. When the TCC, the TCM, or the transmission fluid is faulty, the car’s internal sensors will detect the subsequent break in the circuit and log code P1740. The code is more common in older cars regardless of make and model.
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What Are the Symptoms of a P1740 Code?
Error code P1740 is usually characterized by drivability issues, since it affects both the engine and transmission. Depending on how serious the problem is, the following symptoms may occur:
- The engine may keep stalling as you drive
- Decreased fuel economy
- Shifting problems
- Transmission may shudder or shake when you stop or accelerate
- Problems getting in and out of certain gears
- The torque converter may fail to engage, or disengage while the car is in motion, effectively bringing the car to a stop
- Regular overheating of the transmission
- Check engine light comes on
What Are Some Causes of a P1740 Code?
The most probable cause of a P1740 code is a faulty torque converter. The second most common cause of the problem is contaminated transmission fluid.
Remember, torque converters are fluid couplers and primarily use transmission fluid. If the fluid is contaminated, overheated, or even too low, the impeller pump in the converter will not be unable to spin the engine’s crankshaft as fast as it should, which will register as an error in the ECU.
Other potential causes of a P1740 error code include internal transmission damage, faulty PCM, and a damaged or malfunctioning torque converter clutch solenoid. A faulty engine or ECU may also trigger the code.
How Serious Is the P1740 Code?
A P1740 diagnostic code is a very serious issue as it can affect how both your engine and transmission work. If the problem is caused by a faulty torque converter, which you can’t tell unless you do a diagnosis, your car will burn gas at a much higher rate than you are used to.
If you don’t get the issue sorted soon enough, the malfunctioning converter may cause the transmission system to fail or get damaged, which means you will have to dig much deeper into your pockets to sort out the problem.
Can I Still Drive with a P1740 Code?
You can drive with the error code P1740, but it is not a guarantee that you will have a smooth ride.
A failed or malfunctioning torque converter is a serious issue, as it means power from your engine is not multiplied and transferred to the transmission at the required levels. The end result is that the transmission would need more time to engage the engine, leading to problems like delayed or harsh shifts.
You will also have problems switching between gears, and if the converter disengages or fails to engage with either the engine or transmission, your vehicle will stall.
How Easy Is It to Diagnose a P1740 Code?
While a P1740 error seems like a simple fix, in reality, it’s not something you want to do by yourself as the risk of misdiagnosing the problem is very high.
Ideally, hire a professional to do the diagnosis for you. In most cases, they will start by checking the transmission fluid to make sure it is neither too low nor contaminated. If the fluid is the problem, which is very likely, the error code will disappear as soon as the technician does a fluid change.
In case the transmission fluid is not the problem, the technician will proceed to check whether the TCM and ECU are working properly using a scan tool. They may also inspect all the wires and connections between circuits, and test if there is connectivity between them. The torque converter clutch solenoid could also be part of the problem, and your technician will check and test it too.
How Difficult Is It to Inspect a P1740 Code?
Once the problem has been properly diagnosed, it isn’t that hard to inspect, and therefore get rid of a P1740 error code.
Thereafter, it’s simply a matter of replacing the damaged parts. In most cases, the solution rests in replacing the torque converter, the clutch, or the torque converter clutch solenoid. Installing a new transmission fluid filter or replacing the fluid may also work if bad fluid is the problem.
Your technician may also recommend an overhaul of the transmission system or even replacing the powertrain control module.
Need Additional Help with Your P1740 Code?
As much as code P1740 is devastating, it is also preventable. It is therefore important to take your vehicle for regular inspection at a credible service center in your area.
And if you are interested in learning more about other code errors and how to manage them, check out the ODB-II Code list.
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