P0121 on a 2022 GMC Sierra 1500
Throttle Position Sensor Range / Performance
P0121 on a 2022 GMC Sierra 1500 indicates throttle position sensor range / performance. It usually stays drivable short-term but should be diagnosed promptly. The most common cause is worn throttle position sensor (mechanical tps wear) (typically $100–$400). Confirm the root cause before replacing parts.
What does P0121 mean on a 2022 GMC Sierra 1500?
P0121 is set when the engine control module sees the throttle position sensor signal moving outside its expected range or changing in a way that does not match other inputs (MAP, MAF, engine load). The TPS reports where the throttle blade is — inputs like accelerator pedal position, engine load, and idle control all depend on accurate TPS readings. Bad TPS data triggers reduced-power or limp mode on many vehicles.
This guide covers P0121 across the 2020-2024 GMC Sierra 1500 generation — the symptoms, causes, and diagnostic steps below apply to every model year from 2020 through 2024.
Is it safe to drive a 2022 GMC Sierra 1500 with P0121?
In most cases a 2022 GMC Sierra 1500 stays drivable for short trips with P0121 active, but diagnose and repair it promptly. This is a high-severity code — ignoring it can lead to further damage or a failed emissions test.
What are the symptoms of P0121 on a 2022 GMC Sierra 1500?
- Check Engine Light is illuminated
- Throttle hesitation or surging at light pedal input
- Stalling when coming to a stop
- Reduced engine power / limp mode
- Erratic or hunting idle
- Slow or absent throttle response
- On electronic-throttle vehicles, may set ETC fault / wrench icon
What causes P0121 on a 2022 GMC Sierra 1500?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Worn throttle position sensor (mechanical TPS wear) | Most common | $100–$400 |
| Carbon buildup in the throttle body causing the blade to bind | Common | $20–$200 |
| Corroded TPS connector or damaged signal wiring | Common | $50–$250 |
| Failed electronic throttle body (combined ETB / TPS unit) | Common | $250–$800 |
| TPS sensor needs reset / relearn after battery disconnect | Occasional | $0–$100 |
| Damaged accelerator pedal position sensor (separate code in some cases) | Occasional | $200–$600 |
| PCM input fault (rare) | Rare | $400–$1,500 |
How to diagnose this on a 2022 GMC Sierra 1500
-
Identify whether this is a cable or electronic throttle
Older vehicles use a cable from the gas pedal to the throttle body, with a TPS sensor that reports actual blade position. Modern vehicles use electronic throttle control (ETC) — pedal position is one sensor, throttle blade position is another, and the ECM controls the motor. The diagnostic differs.
Tools: Vehicle-specific service information
-
Watch TPS voltage sweep with the scan tool
With the key on and engine off, slowly press the throttle from closed to wide open while watching the TPS voltage PID. A healthy sweep is smooth and linear, typically 0.5 V at closed throttle and 4.5 V at wide-open. Glitches, dropouts, or a jumpy reading confirm a worn sensor.
Tools: Scan tool with TPS PID
-
Clean the throttle body
Carbon buildup inside the throttle body causes the blade to stick or close incompletely, which gives bad TPS readings even with a perfect sensor. Use throttle body cleaner (NOT carb cleaner — too aggressive on electronic throttle coatings) and a soft brush. On electronic throttle, perform a relearn after.
Tools: Throttle body cleaner, Soft-bristle brush, Shop towels
-
Perform a throttle position relearn
Battery disconnection, ECM reset, or throttle body cleaning requires a relearn procedure on most modern vehicles. The procedure varies — typically key on, wait 30 seconds, start the engine, idle 5 minutes. Some vehicles need a bidirectional scan tool to perform an idle relearn.
Tools: Service manual procedure, Bidirectional scan tool (some vehicles)
-
Inspect the connector and signal wiring
Unplug the TPS / ETB connector and inspect for water intrusion, corrosion, or bent pins. Engine-bay-mounted connectors fail with age. Apply dielectric grease on reinstall.
Tools: Electrical contact cleaner, Dielectric grease
NHTSA complaints & recalls for the 2022 GMC Sierra 1500
Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2022 GMC Sierra 1500. Use these to gauge how common a problem is on your specific vehicle before you start chasing GMC Sierra 1500 diagnostics.
- ENGINE 207
- POWER TRAIN 92
- STRUCTURE 90
- ELECTRICAL SYSTEM 75
- UNKNOWN OR OTHER 70
6 active recalls
- EXTERIOR LIGHTING:BRAKE LIGHTS Jun 2022
General Motors (GM) has decided that certain 2022 model year Chevrolet Silverado, and GMC Sierra vehicles equipped with an accessory sport bar. The accessory sport bar contains a high-mounted brake light that may not function. In addition, it may block the vehicle's existing hi…
NHTSA campaign 22V463000 - EXTERIOR LIGHTING:LIGHTING CONTROL MODULE:SOFTWARE Dec 2022
General Motors, LLC (GM) is recalling certain 2020-2023 Cadillac CT4 and CT5; 2021-2023 Buick Envision; and 2022-2023 Cadillac Escalade and Escalade ESV, Chevrolet Silverado 1500, Suburban, Tahoe, GMC Sierra 1500, Yukon, and Yukon XL vehicles. The daytime running lights (DRLs) m…
NHTSA campaign 22V903000 - POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE Oct 2024
General Motors, LLC (GM) is recalling certain 2020-2022 Chevrolet Silverado 1500, 2500, 3500, GMC Sierra 1500, 2500, 3500, 2021 Cadillac Escalade, Escalade ESV, Chevrolet Tahoe, Suburban, GMC Yukon, and Yukon XL vehicles equipped with diesel engines. The transmission control val…
NHTSA campaign 24V797000 - STRUCTURE:BODY:BUMPERS:ACTIVE SHUTTERS/GRILL Feb 2025
General Motors, LLC (GM) is recalling certain 2022 GMC Sierra 1500 vehicles equipped with chrome front grille deflectors. The attachments that hold the front grille deflectors in place may fracture, resulting in grille detachment.…
NHTSA campaign 25V060000
How do I fix P0121 on a 2022 GMC Sierra 1500?
- Clean the throttle body with throttle-body-safe cleaner
- Perform a throttle / idle relearn procedure
- Replace the TPS or the electronic throttle body assembly
- Repair damaged TPS connector or wiring
About the 2020-2024 GMC Sierra 1500
The 2020-2024 GMC Sierra 1500 was commonly sold with the following powertrains: 5.3L V8, 6.2L V8, 2.7L Turbo I4, 3.0L Duramax I6 Diesel. Common trims include Pro, SLE, Elevation, SLT, AT4, Denali.
When P0121 means “clean the throttle body” vs “replace the throttle body”
Approximately half of P0121 cases on vehicles over 80,000 miles resolve with a throttle body cleaning and relearn. The other half require sensor or assembly replacement. The deciding test: after cleaning, does the TPS voltage sweep smoothly from closed to wide-open without glitches? If yes, the part is good. If no, replace.
Direct-injection engines and throttle body coking
Direct-injection engines (which inject fuel directly into the cylinder, bypassing the intake) build up carbon on the back of intake valves AND on the throttle body. Coking on the throttle body causes the blade to close incompletely, which sets P0121 even with a perfect sensor. Cleaning becomes part of routine maintenance on these engines, often required every 30–50k miles.
Why P0121 needs a relearn after the fix
Modern electronic throttle systems memorize the closed-throttle position as a calibration point. When the throttle body is cleaned, removed, or replaced, the stored position no longer matches reality. A relearn procedure tells the ECM to re-record the new closed position. Without it, the engine may idle high, surge, or set P0121 again within a few drive cycles.