P0121 GMC Code - Throttle Position Sensor 1 Performance
Quick Answer
The Throttle Body Assembly contains a contact-less inductive throttle position sensing element that is managed by a customized integrated circuit. Common causes include Faulty Throttle Body Assembly, Throttle Body Assembly harness is open or shorted, Throttle Body Assembly circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0121 GMC indicates Throttle Position Sensor 1 Performance.
- Common causes
- Common causes include Faulty Throttle Body Assembly, Throttle Body Assembly harness is open or shorted, Throttle Body Assembly circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0121 GMC Description
What are the Possible Causes of the DTC P0121 GMC?
- Faulty Throttle Body Assembly
- Throttle Body Assembly harness is open or shorted
- Throttle Body Assembly circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0121 GMC?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0121 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Information for Specific GMC Models
- P0121 2014 GMC Sierra — Throttle Position Sensor 1 Performance
- P0121 2015 GMC Sierra — Throttle Position Sensor 1 Performance
- P0121 2016 GMC Sierra — Throttle Position Sensor 1 Performance
- P0121 2017 GMC Sierra — Throttle Position Sensor 1 Performance
- P0121 2018 GMC Sierra — Throttle Position Sensor 1 Performance
Frequently Asked Questions about P0121 GMC Code
1. What are the common symptoms of OBDII code P0121 GMC (Throttle Position Sensor 1 Performance)?
- Common symptoms include issues with acceleration, stalling, rough idling, and decreased fuel efficiency.
2. What are the possible causes of OBDII code P0121 GMC?
- The code P0121 is often triggered by a faulty throttle position sensor, a damaged wiring harness, or a problem with the vehicle's electronic control module.
3. How can I diagnose the cause of OBDII code P0121 GMC?
- You can diagnose the issue by using an OBDII scanner to read the fault codes, checking the throttle position sensor for proper operation, and inspecting the wiring for any damage or loose connections.
4. Can a dirty throttle body cause OBDII code P0121 GMC to appear?
- Yes, a dirty throttle body can disrupt the sensor's readings and potentially trigger code P0121. It's recommended to clean the throttle body as part of the diagnostic process.
5. What are some repair tips for fixing OBDII code P0121 GMC?
- Repair tips include replacing the throttle position sensor, repairing any damaged wiring, cleaning the throttle body, and ensuring proper connections between components.
6. Is it safe to continue driving with OBDII code P0121 GMC present?
- It's not recommended to continue driving with code P0121 active, as it can lead to further damage to the engine and affect the vehicle's performance and fuel efficiency.
7. How much does it typically cost to repair OBDII code P0121 GMC?
- The cost of repairs for code P0121 can vary depending on the underlying issue, but it generally ranges from $100 to $300 for parts and labor.
8. Can I reset OBDII code P0121 GMC with a simple disconnect of the battery?
- Disconnecting the battery may temporarily reset the code, but it's important to diagnose and address the root cause to prevent it from reoccurring.
9. Will code P0121 GMC cause the vehicle to fail an emissions test?
- Yes, code P0121 can cause the vehicle to fail an emissions test due to the impact on engine performance and emissions control.
10. How long does it typically take to repair OBDII code P0121 GMC?
- The time to repair code P0121 can vary based on the specific issue, but most repairs can be completed within a few hours to a day by a qualified mechanic.
Discuss the causes and fixes for P0121 GMC OBDII Code
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be nice to see the bad part at the location on the vehicle so i could replace it myself
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We may be able to help you with that. What model, year and engine is your GM?
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check engine light came on. went to auto parts store and they gave me the po121 code throttle/pedalposition. looked at the gas pedal and it has an electric part the pedal goes into. i unplugged it to check for visible defects. found nothing. started the truck(2009 gmc sierra wk truck) and dash read" engine power reduced" turned truck off plugged it back in and dash read the same. unhooked/ rehooked up battery dash reading was gone, still have check engine light on. have no clue how to test for a bad engine control module or throttle position sensor. help? thnx
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On your GMC, the throttle position sensor is part of the throttle body. You could try cleaning the throttle body and clear the code. If the code comes back, you may have to replace the throttle body to fix the problem.
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Hello
I am having the same problem with my 2007 GMC Denali.I replaced the
throttle sensor and the check engine remains on.The reading I keep receiving
is the PO121 code.What can I do?
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