C2021 Code - Tire 1 Air Pressure Decrease
Quick Answer
The Tire Pressure Monitor (TPM) system checks the tire pressures of all 4 road wheels when the vehicle is driven at speeds above 25 mph (40 km/h), and warns in the event of a loss of pressure by means of a low tire pressure warning light. Common causes include Tire pressure not to factory specifications, Faulty Tire Pressure Transmitter, Faulty Tire Pressure Monitor System (TPMS) Control Module. 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
- C2021 indicates Tire 1 Air Pressure Decrease.
- Common causes
- Common causes include Tire pressure not to factory specifications, Faulty Tire Pressure Transmitter, Faulty Tire Pressure Monitor System (TPMS) Control Module.
- 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 C2021 Description
What are the Possible Causes of the DTC C2021?
- Tire pressure not to factory specifications
- Faulty Tire Pressure Transmitter
- Faulty Tire Pressure Monitor System (TPMS) Control Module
How to Fix the DTC C2021?
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.
Code Tech Notes
If the warning light is still on after adjusting tire pressure, check for a damaged tire and repair as necessary. If warning light blinks 25 times and then illuminates, and there is not a tire without a tire pressure sensor installed, there is a malfunction in the TPM system. See appropriate manufacturer service information.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the C2021 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.
Need more information about the C2021 code?
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Need Help with the Code?
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Information for Specific Makes
- C2021 Subaru — Tire 1 Air Pressure Decrease
Frequently Asked Questions about C2021 Code
1. What are the common symptoms of OBDII code C2021 (Tire 1 Air Pressure Decrease)?
- The common symptoms include the Tire Pressure Monitoring System (TPMS) warning light illuminating on the dashboard and a noticeable decrease in tire pressure in one specific tire.
2. What are the possible causes of OBDII code C2021?
- The code C2021 is typically triggered when there is a significant decrease in air pressure in the tire designated as "Tire 1." This could be due to a leak in the tire, a faulty TPMS sensor, or issues with the tire valve.
3. How can I diagnose the cause of OBDII code C2021?
- To diagnose the cause of the code C2021, you can start by visually inspecting Tire 1 for any visible damage or punctures. You can also use a tire pressure gauge to check the actual air pressure in the tire compared to the recommended pressure.
4. Can low outdoor temperatures trigger OBDII code C2021?
- Yes, low outdoor temperatures can cause a temporary decrease in tire pressure, which may trigger the code C2021. It is recommended to check and adjust tire pressure according to the manufacturer's guidelines in such situations.
5. How can I reset OBDII code C2021 after addressing the tire pressure issue?
- Once you have addressed the tire pressure concern in Tire 1, you can reset the OBDII code C2021 using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes to clear the error code.
6. What are the potential risks of ignoring OBDII code C2021?
- Ignoring OBDII code C2021 can lead to driving with an underinflated tire, which can compromise vehicle handling, fuel efficiency, and overall safety. It is essential to address the issue promptly to prevent further damage.
7. Can a faulty TPMS sensor cause OBDII code C2021?
- Yes, a faulty TPMS sensor that is not accurately detecting tire pressure changes in Tire 1 can trigger OBDII code C2021. In such cases, replacing the TPMS sensor may be necessary to resolve the issue.
8. Is it safe to drive with OBDII code C2021 present?
- It is not recommended to drive with OBDII code C2021 present, as it indicates a potential issue with tire pressure in Tire 1. Driving with an underinflated tire can pose safety risks and cause further damage to the tire.
9. How often should I check my tire pressure to prevent OBDII code C2021 from recurring?
- It is recommended to check your tire pressure at least once a month and before long trips to prevent OBDII code C2021 from recurring. Proper tire maintenance can help avoid issues related to tire pressure imbalance.
10. Can overinflating Tire 1 cause OBDII code C2021?
- Yes, overinflating Tire 1 can potentially trigger OBDII code C2021 as it can lead to excessive pressure that the TPMS system may interpret as a significant air pressure decrease. Be sure to follow the manufacturer's recommended tire pressure guidelines.
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