Error Code P2121: What It Means & What To Do?

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See the error code P2121? Don’t know what to do? Well, only for our customers we have written here all that you need to know about the error code. This error code is stored whenever the PCM receives a reading that fails to fall within the manufacturer’ specifications from the throttle actuator control motor circuit. The malfunction indicator lamp illuminates too. It should be noted that in some models the MIL illuminates immediately, while in others it illuminates after a number of drive cycles with failure.

The electronic throttle control system (ETCS) performs the function of controlling the throttle valve opening. The accelerator pedal position sensor (APP) transmits a signal to the engine's control module (informing the PCM how much power the driver is asking from the engine) as soon as the driver presses the accelerator pedal. The PCM then commands the throttle plate to open accordingly. When the APP sensor fails to open according to the requirements while the accelerator pedal is pressed or released, the PCM registers it and stores an error code P2121. The PCM, at times, also puts the engine into the "limp home mode" therefore reducing the power available from the engine to avoid any unwanted acceleration.

What causes this problem with the Throttle Position Sensor D Circuit Range/Performance?

• A damaged throttle actuator control motor
• A distorted throttle position actuator
• A possible failure in the throttle position sensor or pedal position sensor
• The wiring or connectors in throttle actuator motor or controller area network (CAN) bus harness corroded, open or short circuited
• A disconnected control module ground strap
• A damaged or broken ground wire

1. Throttle position sensor - Having problems with the throttle position sensor? Experiencing problems like a low acceleration? Rough or slow idle? Stalling? Don’t you worry, Parts Avatar has it all. A faulty throttle position sensor could end up being the root cause stimulating the error code P2121.
2. Switch circuit - Check engine light illuminated? Alarmed? A whole lot of problems like no-start condition and car stalling (even while driving) follow a malfunctioning switch circuit. Log into Parts Avatar for your new switch circuit now!
3. Intake manifold tuning valve - A distorted intake manifold tuning valve can end up being the chief host inviting the error code P2121. So replacing one can be one of the wisest decisions to avoid a problematic system.
4. Powertrain control module - A malfunctioning PCM? Well, do you have any idea about the extent to which it can damage your system? A faulty powertrain control module brings along issues like a malfunction in the functioning of the entire engine, also the sparks and ignition timing from the spark plugs are controlled and received by the PCM. So to avoid a whole lot of repairs, we simply advise you to change your PCM now. Log into Part Avatar for best quality PCMs at the best prices.
5. Accelerator pedal position sensor - A failed or broken accelerator pedal position sensor can often invite problems like erratic engine behaviour or result in an inefficient engine. Now get your new accelerator pedal position sensor right at your doorstep with Parts Avatar. Tune in now.
6. Engine control module - This essential unit, if faulty should be changed right away as it brings along a lot of problems including difficulties in starting the vehicle, erratic idle and a misfiring condition too. Now get your new ECM delivered easily with Parts Avatar. Tune in now!

It is essential to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P2121 here:

Common Symptoms

• Black smoke emitting at startup
• A bad acceleration
• Chances of a misfire at idle
• At times, one may notice a forced shutdown
• A strained idle
• At times, a start/stall condition
• A difficulty to start or a no start condition

Here are some ways with the help of which you will be able to correct the OBD Code P2121

• Repair or replace a throttle body
• Replacements or repairs should be performed of the throttle actuator motor
• A damaged pedal position sensor should be repaired or replaced as per the requirements

There is no need to be anxious as Parts Avatar – Car Parts Online is here to help you out! We have high grade position sensor, switch circuit, tuning valve, PCM, ECM, pedal position, fuel injectors, fuel injector harness, body control module, injection pump and a lot more for our precious customers.

Here are some steps which you should follow in order to diagnose this fault code:

For an accurate diagnosis, all that is required is an OBD-II scanner/code reader, digital volt/ohmmeter (DVOM), oscilloscope and manufacturer’s service manual. It should be noted that the code P2121 is valid for the vehicles that have an electronically controlled “drive by wire” throttle body installed. These kinds are designed with a sensor built on the pedal arm that further transmits voltage signal to the PCM or other related controller. According to the conditions, this is what orders the throttle body to open or close. By changing voltage and the polarity, the PCM allows the throttle actuator motor in the required directions. A gear is turned that further connects with a larger gear, enabling the throttle plate to open quickly and slowly depending on the driver’ input as the throttle actuator turns.

• Start with performing a visual inspection of all the wirings and the connectors
• Any electrical components that are damaged, loose, burnt or shorted should be changed or repaired as per the requirements
• Connect the scanner/code reader to the diagnostic connector, if all the system wiring, connectors and components are working in order. Any stored codes and freeze frame data should be registered. The codes should be cleared and the vehicle should be test driven to see if the code returns. On some vehicles multiple drive cycles may be needed to illuminate the MIL
• The throttle position sensor electrical connector should be tested by disconnecting it from the sensor
• A DVOM should be employed to test the voltage and ground signals. All that is required is a 5-volt reference signal and a battery ground. One can access the exact wiring diagrams and connector views by using manufacturer’s service manual
• The connector at the PCM should be disconnected if no reference voltage and/or ground are found
• All the related controller connectors should be tested for resistance and continuity.all the shorted or loose circuits should be repaired or replaced as per requirements
• The codes should be cleared the vehicle should be test driven
• The connector at the PCM should be disconnected if voltage/ground signals are present. Restore the motor and the codes should be cleared and the vehicle should be retested
• At times the entire throttle body might need a replacement including the actuator motor and throttle position sensor
• The pedal sensor replacement might also require replacement along with a throttle body replacement
• Use an oscilloscope to regulate pedal sensor operation (if searching for abnormal spikes or glitches in voltage) if the voltage/ground signals fall within manufacturer’s specs

Common Mistakes When Diagnosing the P2121 Code

Here we have listed a few common mistakes that should be avoided while you diagnose the code:

It should be noted that most of the times the mechanics solve and treat the symptoms rather than the actual cause of the problem when numerous codes are recorded. When followed by a controller communication code, codes related to lean exhaust, engine misfires, fuel injectors or numerous other codes can often be misdiagnosed. Also, it is advised to diagnose the codes in order in which they were stored (as that increases the chances of an accurate diagnosis). You can determine the order in which the codes were stored by using the scanner freeze frame function.