If you own a Toyota truck, you may have seen the C1201 code pop up on your dashboard. This can be a bit confusing, especially if you don’t know what it means.
In this article, we will explain what the C1201 code is and what its symptoms are. We will also provide tips on how to fix it yourself if you’re comfortable doing so. Keep reading to learn more!
C1201 code is as confusing as it sounds. The light could come on for several reasons, including a leaky gas cap, faulty brake light switch, engine control system malfunction, or faulty wheel speed or oxygen sensor.
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The code C1201 stands for “Engine Control System Malfunction.” This is a generic trouble code, which means it applies to all vehicles equipped with the OBD-II system, particularly those made since 1996 up to the present.
When the engine control system malfunctions, it is detected through a control area network (CAN). The vehicle falls back on its limp mode, the failsafe mode designed to allow the car to be driven to a safe location.
The engine runs at reduced power in this mode, and the transmission is locked in second gear. The check engine light will also be illuminated on the dashboard.
What Triggers C1201 Code in Toyota?
C1201 code is as confusing as it can get. One can never know for sure what triggers the code. However, Toyota has released a TSB (technical service bulletin) that might provide some clarity on the matter.
The TSB #EG013-03 states that C1201 can be caused by a leaky gas cap, faulty brake light switch, engine control system malfunction, or faulty wheel speed or oxygen sensor.
Let us understand the relationship between the C1201 code and these reasons:
1. Evaporator Emission Control System Leak:
A gas cap that is not tightened properly can cause the evaporator emission control system (EVECS) to leak. This will trigger the C1201 code. It can also trigger some other codes, but those are not our topic today.
The evaporative emission control system is a system that controls the release of vapors from a vehicle’s fuel system. EVAP canister is designed to prevent the escape of vapors into the atmosphere, and it does this by routing the vapors back into the engine’s cylinders, where they are burned.
Now several components make up the EVECS, and each one has a role. The gas cap is one of these; its job is to seal the fuel system so that vapors cannot escape.
When the gas cap is not tightened properly, it allows vapors to escape into the atmosphere. The EVAP system then detects these vapors, and the C1201 code is triggered.
2. Faulty Brake Light Switch:
A brake light switch is a switch that is connected to the brakes of a vehicle. The switch is activated when the brakes are applied, and the brake lights are illuminated. The switch is usually located near the pedal or handlebar.
When the brake light switch is activated, it sends a signal to the Brake Control Module (BCM). The BCM then activates the brake lights. The switch may also trigger other safety features such as the traction control system or vehicle stability control.
So, when the brake light switch is faulty, the VSC and TCS will not be activated. The BCM may not receive the signal that the brakes are being applied, which can cause the C1201 code to be triggered.
3. Anti Lock Brake System Malfunction:
The anti-lock brake system (ABS) is a safety feature that prevents the wheels from locking up when the brakes are applied. ABS uses sensors to detect when a wheel is about to lock up and then applies the brakes to that wheel only.
If there is a problem with the ABS, it can cause the C1201 code to be triggered. ABS problems can be caused by various things such as a faulty sensor, a bad ABS control module, a faulty ABS pump or low brake fluid.
4. Wet Wheel Speed Sensor:
The wheel speed sensor is used by the ABS to detect when a wheel is about to lock up. The sensor is located on the hub of the wheel, and it measures the speed of the wheel.
If the sensor gets wet, it can cause the C1201 code to be triggered. Wet sensors can be caused by water or other fluids getting on them. This can happen if you drive through a puddle or your car was recently washed.
5. Faulty Oxygen Sensor:
If the oxygen sensor is faulty, it can trigger the C1201 code. Oxygen sensors can fail for various reasons, such as age, contamination, or a bad connection.
Oxygen sensors are used in modern vehicles to help optimize the air-fuel mixture. The oxygen sensor creates a voltage signal corresponding to the amount of oxygen in the exhaust stream.
This signal is then used by the vehicle’s computer to adjust the air-fuel mixture to optimize performance and fuel economy.
If the air-fuel mixture is too rich, it can cause problems such as increased emissions, decreased fuel economy, and reduced power. If the mixture is too lean, it can cause engine damage.
What are the Symptoms of the C1201 Toyota Code?
Similar to the broad range of reasons that can trigger the C1201 diagnostic trouble code, there are also a variety of symptoms that can be associated with it. Some of the most common symptoms include:
- The check engine light is illuminated.
- The ABS light is illuminated.
- The traction control light comes on.
- The traction control system is disabled.
- Toyota stability control system malfunctions.
- There is decreased braking performance.
- The vehicle has reduced power.
- The fuel economy is decreased.
How to Fix C1201 Code?
There are a few different ways that you can go about fixing the C1201 code. Some of the most common fixes include:
- Checking and tightening the leaky gas cap.
- Changing the seal on the gas cap.
- Try resetting the electronic stability control system.
- Replacing the gas cap with an OEM one.
- Replacing the brake light switch.
- Bleeding the brakes.
- Replacing the ABS pump.
- You can try to perform zero point calibration procedure.
- Draining and refilling the brake fluid reservoir.
- Replacing the oxygen sensor.
- Troubleshooting and repairing the wiring harness.
As you can see, there are a few different options for fixing the C1201 code. The best way to figure out what is causing your vehicle to trigger the code is to take it to a qualified mechanic or dealership for diagnosis.
C1201 Toyota Fixing Cost
The cost of fixing the C1201 code will vary depending on what is causing it. For example, the cost will be relatively low if you just need to tighten or change the gas cap. Such repair or replacement will cost you under $20.
However, the cost will be significantly higher if you need to replace the ABS pump or bleed the brakes. Replacing an ABS pump will cost you no less than $300.
Most of the time, you don’t need to replace anything. The code appears just because some work was performed on your vehicle and some sensor has gone off.
You take your car to a mechanic, who will hook it up to a scanner. The mechanic will then reset the code. This will cost you about $100 to $150.
Ultimately, the best way to get an accurate cost estimate is to take your vehicle to a qualified mechanic or dealership for diagnosis.
The C1201 code is a relatively common one that can be triggered by a variety of different issues, which include: a faulty gas cap, a leak in the brake light switch, a problem with the oxygen sensor, or a bad speed sensor.
C1201 poses a serious threat to your safety as it can disable the traction control system and reduce braking performance.
The best way to figure out what is causing your vehicle to trigger the code is to take it to a qualified mechanic or dealership for diagnosis. They can properly diagnose the issue and recommend the best course of action.
We hope this article has helped you better understand the C1201 code and what it means for your vehicle. If you have any further questions, please don’t hesitate to reach out to us. We would be more than happy to help!
Frequently Asked Question
Can you drive with a C1201 Code? How Long?
Yes, you can drive with a C1201 code, but it is best to get it checked out as soon as possible. It is a code that exhibits mild symptoms and can be easily fixed.
However, if left unchecked, it can lead to more serious problems down the road. Therefore, it is always best to get it checked out and repaired as soon as possible.
We believe you should not drive over 60 mph and no more than 1,000 miles with the C1201 code. If you have to drive further than that, we advise you to get the car checked out by a professional mechanic as soon as possible.
What is an engine control system?
An engine control system is a computerized system that regulates the operation of an internal combustion engine. The system controls the engine’s ignition timing, fuel injection, and other important functions.
The engine control system is an integral part of modern vehicles. It helps to ensure that the engine runs smoothly and efficiently. By optimizing the engine’s performance, the system can help improve fuel economy and reduce emissions.
There are many different types of engine control systems, but all share some basic components. These include sensors that monitor various aspects of the engine, a central processing unit (CPU) that interprets the sensor data, and actuators that adjust the engine’s operation based on the CPU’s commands.
Will the C1201 Toyota code disappear on its own?
Yes, it is known to happen that the C1201 Toyota code disappears on its own after some time. This is especially true if the code was caused by a loose gas cap, a problem with the oxygen sensor, or a wet speed sensor.
However, if the code was caused by a more serious issue, such as a problem with the ABS pump or the brakes, it is unlikely that the code will disappear on its own. In such cases, it is best to take your vehicle to a qualified mechanic or dealership for diagnosis and repair.