A C1201 code is almost always caused by a poor electrical connection or a wiring harness that is damaged physically. These components control the normal operating voltage levels, so anytime there is a disruption to the circuit, the ABS module will pick up on it since it is continuously tracking its performance. Another possible cause of the C1201 code is a stuck or defective solenoid pump that can disrupt the braking mechanism of the ABS and the traction control system. This also applies to codes C1198-C1200, as they can be triggered by a poor or intermittent connection at the ABS module as well.

This also ties into codes C0040 and C0034-C0035 since they have to do with another component of the ABS and that’s the wheel speed sensor, which informs your ABS of the speed at which your wheels are traveling. The ABS module monitors four wheel speed sensors, which produce an alternating current voltage. A disruption in this circuit causes these sets of codes to trigger. These codes have to do with issues with the right front wheel only and when the communication between this sensor and the ABS module is interrupted, your ABS is unable to effectively perform its braking assist function.

Codes C1095-C1098 also are related to ABS issues as they are triggered when the ABS hydraulic pump motor circuit fails. Since the ABS module monitors the rotational speed through the wheel sensors, whenever it detects an impending wheel lock, it will direct the right amount of brake pressure to the appropriate caliper. This is done by triggering the hydraulic control unit to open and close the right solenoid valves. Once the affected wheel is back to normal speed, the ABS module returns the solenoid valves to their normal position, allowing regular braking patterns to continue. So, any damage to wheel sensors or damaged or open wiring circuits will cause these sets of codes to trigger and affect your vehicle’s ABS functionality.

As for the C1241 code and the related codes of C1238-C1240, these are related to power supply circuit issues with your car’s computer system that monitors the brake assembly. They are stored when the voltage that goes to the Skid Control ECU is lower than the factory specifics call for due to issues with the battery level or alternator circuit. If the battery is operating on a low charge then this is most likely caused by a faulty alternator or the power circuit from your alternator to your battery could also be shorting, as is indicated by the C1240 code.

Your vehicle battery could also be losing power slowly over time due to poorly maintained terminal ends, so it’s important to properly maintain your battery. It’s important to note, though, that the ABS is powered by an electrical circuit and so any drops in battery voltage levels will cause the ECU to initiate its fail-safe function so that the ABS doesn’t altogether stop working. However, it’s likely that in these instances ABS functionality can cease, limiting the hydraulic pressure to each wheel brake. Once this occurs, your conventional braking system will still function unless there is another debilitating issue like a damaged brake fluid line. To find more details on replacing your car’s battery, visit KBB’s battery replacement page.

A C1201 or any related code sets because your vehicle will still have conventional braking capabilities. It may be hard for us to comprehend now but ABS is still a relatively new feature when you look at the entire history of automobiles. As recently as the 1980s, ABS was not a standard feature in vehicles and wouldn’t be until the 1990s. Driving without ABS could be manageable, having to be much more cautious with your driving habits. This means that good distance between vehicles is a must. You should have your vehicle taken to the nearest service center to address the C1201 and related codes. To find more information on service centers to help with that, visit KBB’s service center list here.

Since the cause of the C1201 code is the ABS inlet valve, repairs will consist of replacing the old valve with a new one. This can be difficult to perform sometimes as the inlet valve is usually integrated into the ABS assembly. This also applies to C0040 and related codes if the wheel speed sensor is in question since it typically is only replaced and not repaired. For C1095 and related codes, more often than not, it requires replacing the hydraulic pump unit. However, if the issue lies with C1238 and related codes, it will require looking at the wiring harnesses and circuit systems leading from the alternator and battery to the ECU. This is a much more meticulous process and not recommended for your average car enthusiast to attempt. This is why it is recommended to contact a technician with related experience repairing these types of circuits so that you can be sure of the repair.