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P0121

Throttle/Pedal Position Sensor A Range/Performance

TPS reading is out of expected range for current throttle position.

SeverityCritical
CategoryEngine
Est. Repair Cost$100–$500
Code TypePowertrain
DIY RepairYes

⚡ Common Causes

  • ›Dirty throttle body
  • ›Faulty TPS
  • ›Worn throttle cable
  • ›Carbon on throttle plate

⚠️ Symptoms

  • ›Surging
  • ›Hesitation
  • ›Erratic idle
  • ›Check engine light

✅ How to Fix — Step by Step

  • Step 1:Clean throttle body with cleaner spray
  • Step 2:Perform throttle body relearn procedure
  • Step 3:Replace TPS
  • Step 4:Replace throttle body

🔧 Diagnostic Tools Required

Using the correct diagnostic tools helps identify the root cause of P0121 before replacing parts unnecessarily. Always confirm the fault using live data and manufacturer-recommended diagnostic procedures.

💡 Pro Tip: After cleaning a throttle body always perform the idle relearn procedure — failure to do so causes rough idle.

Repair Cost Estimate

Full Repair Estimate
$100–$500
DIY Possible?
YES
Severity
Critical

Frequently Asked Questions

What does OBD2 code P0121 mean?+
P0121 stands for Throttle/Pedal Position Sensor A Range/Performance. TPS reading is out of expected range for current throttle position.
What causes code P0121?+
Dirty throttle body; Faulty TPS; Worn throttle cable; Carbon on throttle plate
How do I fix code P0121?+
Clean throttle body with cleaner spray; Perform throttle body relearn procedure; Replace TPS; Replace throttle body
How much does it cost to fix P0121?+
Estimated repair cost for P0121 is $100–$500.
Is P0121 DIY-friendly?+
Yes — P0121 is generally DIY-friendly with basic tools.

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