How to Fix P2122 Trouble Code for Low Throttle Pedal Input Voltage?

[LaSavannah]

p2122 trouble code indicates low throttle pedal input voltage. To resolve this issue, check for any open circuits in the wiring. If the wiring is normal, replace the throttle pedal and then perform computer matching to fix the P2122 trouble code. Here is some relevant information about trouble codes: Definition: Vehicle trouble codes are error codes generated by the car's computer ECU after analyzing a fault. Most trouble codes are caused by sensor malfunctions or poor sensor performance, but some mechanical faults cannot be detected by the ECU. Classification: Automotive trouble codes can be divided into two types: intermittent faults and actual faults. Intermittent faults can usually be cleared if they do not reappear, while actual faults must be repaired before they can be cleared.

[VonPeter]

Don't panic when encountering P2122 trouble code. Last time my car showed this light, I found it was caused by worn-out wiring harness behind the throttle pedal leading to short circuit. First check if the related fuse in the fuse box is blown - the location is usually under the left cover of the driver's seat, look for one labeled 'SENSOR'. If it's intact, inspect the throttle pedal sensor connector; unplug it to check if the contacts are oxidized or blackened. If possible, use a multimeter to measure the voltage of the power supply line - it should normally be around 5V. If the wiring is fine, it's likely the sensor is faulty. Replacing it yourself isn't difficult, but remember to disconnect the negative terminal of the battery first. After repair, remember to clear the trouble code. However, if the wiring harness is worn out, make sure to wrap it securely with insulating tape, otherwise the issue may recur during rainy days.

[DelLucy]

My friend who works in auto repair says that 90% of the time, the P2122 fault is caused by wiring issues. Especially in older cars, the wiring harness from the throttle pedal sensor to the ECU can wear out over time as it rubs behind the steering column. First, use your phone's flashlight to check for any obvious damage on the wiring. Then, focus on three key areas: the condition of the sensor connector, whether the connector on the ECU side is loose, and if the middle section of the wiring has been crushed by aftermarket equipment. If the wiring is intact, there's an 80% chance the internal potentiometer in the sensor is worn out. Remember to perform a sensor matching procedure after installing a new one—some models require you to press the throttle three times after a cold start. Avoid buying off-brand parts; they don’t hold up well in practice.

[BriannaFitz]

To diagnose the P2122 fault, follow a two-step approach. Low voltage indicates a power supply issue—first, check the upstream power sources: the ECU power supply fuse in the engine compartment fuse box and the sensor fuse in the cabin fuse box. If all fuses are intact, then inspect the power supply wiring from the fuse to the sensor for any breaks, especially at the firewall penetration points where wires are prone to damage. If the sensor is faulty, the symptoms are typical: the vehicle may jerk during sudden acceleration but idle smoothly. When replacing the sensor yourself, ensure the pin positions are correctly aligned; installing it backward may trigger other fault codes. Lastly, avoid using WD40 on the contacts as it conducts electricity and can cause further issues.