P0122 on Cadillac: How to Diagnose & Fix
Throttle/Pedal Position Sensor/Switch 'A' Circuit Low Input
1 Cadillac model · 1 documented issue · 1 critical
P0122 on Cadillac by model: symptoms, diagnosis and fix
On some 2008-2011 CTS models the throttle-position sensor can cause the engine to run rough, illuminate the check engine light and/or an engine reduced power message, and reduce engine power. GM recognized the condition with Special Coverage Adjustment 14582, which covered it for 10 years / 120,000 miles from the original in-service date, whichever came first, regardless of ownership.
Common Symptoms
- Engine Power Reduced message on the DIC
- Loss of engine power
- Check engine light
- Engine runs rough
How to Fix
Diagnose the throttle-control fault and inspect its connectors and wiring before replacing parts. For VIN-eligible 2008–2011 CTS vehicles, GM special coverage 14582 applies when DTC P2135, P0121 or P0221 is set and distinguishes Bosch throttle-body replacement from a Hitachi TPS sensor-kit repair; replace a Hitachi assembly only if the kit does not correct the condition. Coverage was limited to 10 years or 120,000 miles from original in-service date, whichever came first. Ask a dealer to verify applicability and any remaining coverage; do not assume a free repair or replace the accelerator pedal without its own diagnosis.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (1)
P0122 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0122 mean on a Cadillac?
P0122 stands for "Throttle/Pedal Position Sensor/Switch 'A' Circuit Low Input." This generic code means the PCM detected a lower-than-expected voltage from the throttle position sensor (or accelerator pedal position sensor) 'A' circuit. This sensor tells the computer how far the throttle/pedal is open so it can manage fuel, timing, and on drive-by-wire systems the throttle itself. A low or lost signal can cause hesitation, surging, poor acceleration, stalling, or limp-home mode, so it should be diagnosed promptly. On Cadillac it is documented across 1 model: CTS.
What are the most common causes of P0122?
The most common causes of P0122 are: Faulty throttle position sensor, Short to ground or open in the TPS signal circuit, Damaged or corroded TPS connector, Loss of reference voltage or bad ground to the sensor, Worn throttle body / TPS contacts, Chafed or pinched wiring harness, Faulty PCM (rare). The specific cause varies by vehicle.
How much does it cost to fix P0122 on a Cadillac?
Repair costs vary widely with the root cause and Cadillac model; each issue on this page carries its own estimate where one is published.
Looking for P0122 on a different make?
View P0122 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.