Throttle/Pedal Position Sensor/Switch “A” Circuit Low Input
Our emissions expert has put together the following information about the P0122 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.
OBD II Fault Code
OBD II P0122
Fault Code Definition
Code P0122 is triggered when the voltage output from the Throttle/Pedal Position Sensor/Switch to the PCM is too low.
The Throttle Position Sensor/Switch is located on the Throttle Body of the Intake Manifold and the Pedal Position Sensor/Switch is located on the Accelerator Pedal. These sensors provide precise input from the driver’s foot in terms of how much power is needed—and how urgently—from the engine.
As the Throttle Position Sensor is rotated from its base resting position to full acceleration, it sends a increasing voltage signal to the Powertrain Control Module (PCM). This decreasing or increasing voltage signal is used by the PCM to manage the Air Fuel Ratio and Spark Timing of the engine as well as other emissions system components.
Symptoms
Check Engine Light will illuminate
In many cases, no abnormal symptoms may be noticed
In some cases, the engine may be hard starting
In some cases, the engine may hesitate during acceleration
Common Problems That Trigger the P0122 Code
Defective Throttle Position Sensor or Switch
Torn or jammed floor mats
Faulty or corroded Throttle/Pedal Position Sensor/Switch wiring or connections
Common Misdiagnoses
Throttle or Pedal Position Sensor is replaced when the real problem is a poor connection or chafed wiring
Pedal Position Sensor is replaced when the real problem is torn or damaged floor mats
Possible Solutions
Some recommended troubleshooting and repair steps are:
Carefully check the throttle position sensor (TPS), wiring connector, and wiring for breaks, etc. Repair or replace as necessary
Check the voltage at the TPS (refer to a service manual for your vehicle for specific information). If the voltage is too low that is indicative of a problem. Replace if necessary.
If recently replaced the TPS may need to be adjusted. On some vehicles the installation instructions call for the TPS to be properly aligned or adjusted, consult a repair manual for specifics.
If there are no symptoms at all, the problem may be intermittent and clearing the code may resolve the issue temporarily. If this is the case then you should definitely check the wiring to be sure it’s not rubbing on anything, grounding, etc. The code may come back.
Other TPS sensor and circuit related DTCs: P0120, P0121, P0123, P0124
Misfire Detection Monitor – Cylinder 12 Misfire
Description:
How does a P0312 code trigger the check engine light? This code will trigger the check engine light as follows:
The misfire detection monitor, a software strategy built into the computer, is designed to detect an engine misfire. The computer can also normally identify the specific cylinder in which the misfire has occurred. A misfire is nothing more than a lack of combustion, which can be caused by poor fuel quality or metering, low compression, lack of spark or unmetered air entering the engine. There are other possible, less obvious causes as well, such as uncommanded Exhaust Gas Recirculatin (EGR), flow. When the misfire monitor detects a misfire, it will trigger the check engine light with the specific cylinder number as the last digit in the P030X code. For instance cylinder 1 misfire is P0301, cylinder 2 is P0302 etc. In this case we are left with a P0312 in the computer memory.
Possible Causes:
Fuel injectors, related wiring, sensors and computer issues
Running out of gas, or poor fuel quality
Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine
Incorrect Fuel Pressure
EGR system concerns: leaking EGR valve or restricted ports
Base engine concerns: low compression, valve train problems and timing issues
Ignition system concerns including, but not limited to:
Faulty spark plugs
Faulty coil or related wiring
Ignition module or related wiring issues
Ignition related sensor faults or wiring issues
Diagnostic Help:
To diagnose a P0312 trouble code we begin by checking for proper fuel and ignition system operation, and then follow up with the less likely causes listed above, such as EGR and EVAP system problems. New style coil on plug applications have a high failure rate, and can be concluded faulty by swapping to another cylinder and checking to see if the misfire moves to that cylinder. This is a quick check if a capable scan tool or oscilloscope is not available. Always make sure the basic maintenance is done first and that things such as the fuel filter, air filter, spark plugs and spark plug wires are in good working order, as these are all possible candidates for a problem. If necessary, check for wiring and component concerns. See our article “Automotive Circuit Testing 101”, if you need more assistance with this. If concern is determined to be intermittent, check out our article on intermittent diagnosis and wiggle test connectors and wiring, attempting to duplicate concern. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instruction.
Misfire Detection Monitor – Cylinder 11 Misfire
Description:
How does a P0311 code trigger the check engine light? This code will trigger the check engine light as follows:
The misfire detection monitor, a software strategy built into the computer, is designed to detect an engine misfire. The computer can also normally identify the specific cylinder in which the misfire has occurred. A misfire is nothing more than a lack of combustion, which can be caused by poor fuel quality or metering, low compression, lack of spark or unmetered air entering the engine. There are other possible, less obvious causes as well, such as uncommanded Exhaust Gas Recirculatin (EGR), flow. When the misfire monitor detects a misfire, it will trigger the check engine light with the specific cylinder number as the last digit in the P030X code. For instance cylinder 1 misfire is P0301, cylinder 2 is P0302 etc. In this case we are left with a P0311 in the computer memory.
Possible Causes:
Fuel injectors, related wiring, sensors and computer issues
Running out of gas, or poor fuel quality
Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine
Incorrect Fuel Pressure
EGR system concerns: leaking EGR valve or restricted ports
Base engine concerns: low compression, valve train problems and timing issues
Ignition system concerns including, but not limited to:
Faulty spark plugs
Faulty coil or related wiring
Ignition module or related wiring issues
Ignition related sensor faults or wiring issues
Diagnostic Help:
To diagnose a P0311 trouble code we begin by checking for proper fuel and ignition system operation, and then follow up with the less likely causes listed above, such as EGR and EVAP system problems. New style coil on plug applications have a high failure rate, and can be concluded faulty by swapping to another cylinder and checking to see if the misfire moves to that cylinder. This is a quick check if a capable scan tool or oscilloscope is not available. Always make sure the basic maintenance is done first and that things such as the fuel filter, air filter, spark plugs and spark plug wires are in good working order, as these are all possible candidates for a problem. If necessary, check for wiring and component concerns. See our article “Automotive Circuit Testing 101”, if you need more assistance with this. If concern is determined to be intermittent, check out our article on intermittent diagnosis and wiggle test connectors and wiring, attempting to duplicate concern. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instruction.
Misfire Detection Monitor – Cylinder 10 Misfire
Description:
How does a P0310 code trigger the check engine light? This code will trigger the check engine light as follows:
The misfire detection monitor, a software strategy built into the computer, is designed to detect an engine misfire. The computer can also normally identify the specific cylinder in which the misfire has occurred. A misfire is nothing more than a lack of combustion, which can be caused by poor fuel quality or metering, low compression, lack of spark or unmetered air entering the engine. There are other possible, less obvious causes as well, such as uncommanded Exhaust Gas Recirculatin (EGR), flow. When the misfire monitor detects a misfire, it will trigger the check engine light with the specific cylinder number as the last digit in the P030X code. For instance cylinder 1 misfire is P0301, cylinder 2 is P0302 etc. In this case we are left with a P0310 in the computer memory.
Possible Causes:
Fuel injectors, related wiring, sensors and computer issues
Running out of gas, or poor fuel quality
Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine
Incorrect Fuel Pressure
EGR system concerns: leaking EGR valve or restricted ports
Base engine concerns: low compression, valve train problems and timing issues
Ignition system concerns including, but not limited to:
Faulty spark plugs
Faulty coil or related wiring
Ignition module or related wiring issues
Ignition related sensor faults or wiring issues
Diagnostic Help:
To diagnose a P0310 trouble code we begin by checking for proper fuel and ignition system operation, and then follow up with the less likely causes listed above, such as EGR and EVAP system problems. New style coil on plug applications have a high failure rate, and can be concluded faulty by swapping to another cylinder and checking to see if the misfire moves to that cylinder. This is a quick check if a capable scan tool or oscilloscope is not available. Always make sure the basic maintenance is done first and that things such as the fuel filter, air filter, spark plugs and spark plug wires are in good working order, as these are all possible candidates for a problem. If necessary, check for wiring and component concerns. See our article “Automotive Circuit Testing 101”, if you need more assistance with this. If concern is determined to be intermittent, check out our article on intermittent diagnosis and wiggle test connectors and wiring, attempting to duplicate concern. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instruction.
Misfire Detection Monitor – Cylinder 9 Misfire
Description:
How does a P0309 code trigger the check engine light? This code will trigger the check engine light as follows:
The misfire detection monitor, a software strategy built into the computer, is designed to detect an engine misfire. The computer can also normally identify the specific cylinder in which the misfire has occurred. A misfire is nothing more than a lack of combustion, which can be caused by poor fuel quality or metering, low compression, lack of spark or unmetered air entering the engine. There are other possible, less obvious causes as well, such as uncommanded Exhaust Gas Recirculatin (EGR), flow. When the misfire monitor detects a misfire, it will trigger the check engine light with the specific cylinder number as the last digit in the P030X code. For instance cylinder 1 misfire is P0301, cylinder 2 is P0302 etc. In this case we are left with a P0309 in the computer memory.
Possible Causes:
Fuel injectors, related wiring, sensors and computer issues
Running out of gas, or poor fuel quality
Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine
Incorrect Fuel Pressure
EGR system concerns: leaking EGR valve or restricted ports
Base engine concerns: low compression, valve train problems and timing issues
Ignition system concerns including, but not limited to:
Faulty spark plugs
Faulty coil or related wiring
Ignition module or related wiring issues
Ignition related sensor faults or wiring issues
Diagnostic Help:
To diagnose a P0309 trouble code we begin by checking for proper fuel and ignition system operation, and then follow up with the less likely causes listed above, such as EGR and EVAP system problems. New style coil on plug applications have a high failure rate, and can be concluded faulty by swapping to another cylinder and checking to see if the misfire moves to that cylinder. This is a quick check if a capable scan tool or oscilloscope is not available. Always make sure the basic maintenance is done first and that things such as the fuel filter, air filter, spark plugs and spark plug wires are in good working order, as these are all possible candidates for a problem. If necessary, check for wiring and component concerns. See our article Automotive Circuit Testing 101, if you need more assistance with this. If concern is determined to be intermittent, check out our article on intermittent diagnosis and wiggle test connectors and wiring, attempting to duplicate concern. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instruction.
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