P0122 Code: Meaning, Symptoms, Causes (& How to Fix it)

Your vehicle engine has different sensors. Your powertrain control module triggers a trouble code when something goes bad with the particular sensor. Your Throttle Position Sensor (TP sensor, TPS, or TPS sensor) plays a vital role in ensuring the efficient working of the engine. As your PCM detects a problem with the signal coming from the TP sensor, it triggers the P0122 code. This article deeply explains the P0122 code, meaning symptoms and causes.  

P0122 Code Definition

P0122 engine code stands for “Throttle Position Sensor/Switch A Circuit Low Input.”

What does the P0122 Code Mean?

The P0122 code indicates that your powertrain control module (PCM) has detected that the signal coming from the throttle position sensor A is lower than the specified limit.

P0122 code

The throttle position sensor is installed on the throttle body to measure the position of the throttle valve.

The throttle position sensor is a device that helps the PCM in regulating the proper fuel injection rate and ignition timing. This sensor performs this job by measuring the air flow rate through the throttle body valve.

The TPS sensor provides a variable resistance depending on the throttle valve opening angle. 

When the PCM of your vehicle gets a low input signal from the TPS sensor than the minimum voltage threshold (typically lower than 0.17 to 0.20 volts), it triggers the trouble code P0122.

Causes of the P0122 Code

  1. Damaged throttle body
  2. Circuit shorted to voltage
  3. A bad throttle position sensor
  4. Loose or damaged connections
  5. Carbon-fouled throttle body
  6. A bad pedal position sensor
  7. A bad throttle position sensor switch
  8. Bad or damaged wiring 
  9. Loose or improperly aligned TPS sensor
  10. Wrong throttle valve opening angle
  11. PCM issues (e.g., the software update is required)

Symptoms of P0122 Code

  • Check Engine Light illumination
  • High, low, or rough idle
  • Engine stalling
  • Engine hesitating while accelerating
  • Hard start
  • Increased emissions
  • Zero or very low acceleration
  • Limp mode

Read More: P0123 Code Symptoms and Causes

How to Diagnose the P0122 Code

You need the following tools to diagnose or fix the P0122 code:

  • Electrical Cleaner
  • Multimeter
  • Auto Repair Manual
  • Diagnostic OBD Scan Tool
  • Basic Hand Tools
  • Throttle body cleaner

Follow the below-given steps to diagnose the P0122 code:

  1. Use an OBD-II scanner to scan the trouble code. Check the freeze frame data to examine the condition of your vehicle. Clear any trouble codes and test the vehicle again to see what comes back.
  2. Remove carbon deposits from the throttle body using a special cleaner.
  3. Properly inspect the connectors and wirings of the TP sensor for damage, corrosion, or short. Damaged wiring usually generates different issues, so it’s probably nothing more than a bad connection.
  4. Repair or replace the damaged connection or wiring, but continue to check the scanner data to ensure the fault has been fully resolved.
  5. Relate the data between TPS sensor  A and B circuits on the scanner. If differences between data points are found, perform the TP sensor accuracy test as suggested by the car manufacturer.
  6. If you couldn’t find any problem in the above steps, the fault code is likely due to a bad TPS sensor. Replace your bad TPS sensor and clear codes.

Common P0122 Code Diagnosis Mistakes

  • Replacing the throttle position sensor without inspecting the wiring and connections
  • Replacing the TPS sensor without making sure it is a problem
  • Not scanning, documenting, and clearing codes, then retesting for them to verify failures
  • No visual inspection of the wirings and connections first
  • Not verifying whether the TPS sensor A and B circuit voltages are within specification before and after repair or replacements.

Repair Cost of P0122 Code

The fixing or repairing cost of the P0122 code varies according to the vehicle model, labor cost, and repair cost of the relevant part. To fix or repair the P0122 code, you may need one or more of the following repairs:

  • TPS sensor connector replacement: $20 to $80
  • Wiring short repair: $20 to $510
  • Throttle body replacement: $15 to $670
  • TP sensor replacement: $90 to $320
  • PCM replacement: $250 to $2,500

FAQ Section

What repairs can fix the P0122 Code?

The following repairs help to fix the DTC P0122:

  • Replacing or fixing the bad or damaged TPS sensor connectors
  • Replacing or cleaning the throttle body
  • Replacing the bad throttle position sensor 
  • Repairing or reprograming the PCM
  • Repairing or replacing the damaged wirings

How serious is the code P0122?

When P0122 occurs, the powertrain control module of your vehicle will go into the failsafe mode to prevent your vehicle’s transmission system and engine from being damaged.

The failsafe mode leads to various drive problems until the repair is complete. According to the manufacturer’s failsafe policy, drivability problems may include stalling, poor engine performance, speed limitation, bucking or jerking, high idle, or lack of acceleration.

Can I drive with a P0122 Code?

Yes, you can drive with trouble code P0122. However, fixing this code as soon as possible is recommended because it may create multiple drivability issues. When this code appears, your PCM shifts your car engine into the failsafe mode or limp mode. 

Some other codes also explain the performance of the throttle position sensor at the “A” position. These codes are given below:

  • P0120 Code: Throttle Position Sensor/Switch A Circuit Malfunction 
  • P0121 Code: Throttle Position Sensor/Switch A Circuit Range/Performance Problem 
  • P0123 Code: Throttle Position Sensor/Switch A Circuit High Input 
  • P0124 Code: Throttle Pedal Position Sensor/Switch (TPS) A Circuit Intermittent

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