P2122: Throttle/Pedal Position Sensor/Switch D Circuit Low

What does P2122 mean?

P2122 sets when pedal track D falls below its lower voltage limit, typically from a short to ground, a missing 5 V reference or a broken signal wire. Limits differ by maker: Ford uses 0.25 V and since 2020 lights both MIL and wrench lamp (in 2012 only the wrench lamp); GM's 2007 tables use 0.325 V with 19 of 39 counts at 12.5 ms (Type A), GM's 2023 table 23OBDG07 0.28 V for 0.2 s; the 2014 VW Passat flags anything under 0.61 V. GM bulletin 14636 extended coverage on 2009-2011 Impala and 2009 LaCrosse pedals with broken solder joints that set this and related codes. P2123 is the high counterpart, P2120 the general circuit code, P2127 the low fault on track E. The ECU limits power and pedal response.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Engine warning lamp and reduced power message
• Pedal feels dead or reacts only slowly
• Cruise control may be unavailable

Common causes

• High Track D signal wire shorted to ground or chafed
• Medium Open or shorted 5 V reference feed to the pedal
• Medium Pedal sensor fault such as a cracked solder joint
• Low Corroded terminals with high resistance

Likelihood is a general estimate across vehicles; your make and model may differ.