C0121 Trouble Code

View C0121 obd/2 error code description and symptoms. C0121 engine photo

The Transmission Range Sensor (also referred to as the PRNDL input an/or neutral safety switch) tells the transmission control module (TCM) an the engine control module (PCM) that the transmission is in park, reverse, neutral, drive, low, 2nd, 3rd etc. It is attached directly to the manual valve of transmission, so when the shift lever is moved from park to drive, the Transmission Range Sensor communicates this critical information to the above mentioned vehicle control module systems.

In most cases, the TCM is integrated into a single housing with the PCM. Nevertheless, the section of the module which controls (automatic) transmission function may be powered up separately. In any case, the TCM is typically powered using switched (only present with the ignition switch in the ON, start, or run position) voltage. This circuit is normally equipped with a fuse, fusible link, and/or a relay. Frequently, the PCM and TCM are powered using the same relay albeit by separate circuits. Access to a reliable vehicle information source will yield necessary details of the TCM power circuit for the specific vehicle in question.

C0121 Error Code Repair Process :

When you turn on the ignition, the Service Engine Soon or Check Engine C0121 light should flash briefly, indicating that the OBD system is ready to scan your vehicle for any malfunctions. After this brief flash, the light should stay off while you drive as long as no problems are detected. If lamp anti-theft indicator circuit open so, you'll be glad to know that your vehicle is equipped with an early warning system that could save you time, money, and fuel in addition to helping protect the lamp anti-theft indicator circuit open.

C0121 is a kind of Chassis Trouble Code

Diagnosing chassis noises can be one of the most frustrating problems technicians face. Fortunately, manufacturers have engineered noise, vibration and harshness (NVH) diagnostic techniques and equipment to find the source of the noise.

Common Causes of C0121

A common cause of code C0121 is the failure of Lamp Anti-Theft Indicator Circuit Open, but there are several other possible causes as well, such as ;

Air fuel ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
Dirty Oil
Fuel injectors harness is open or shorted
Open or short in the VCT circuit

C0121 code for all cars

You can view according C0121 DTC for your car model. We selected several models to see obd2 solutions click and view it.

+C0121 Hyundai Azera

+C0121 Rover Montego

+C0121 Pininfarina Rossa

+C0121 Lloyd Arabella

+C0121 Jaguar Xkr

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