P0121
High SeverityThrottle Position Sensor A Range/Performance
Fuel System
P0121 — Instant Answer
Throttle Position Sensor A Range/Performance
Severity: HIGH SEVERITY
Meaning: The TPS reading does not match expected values based on MAP, RPM, and other inputs. Erratic readings indicate a worn TPS.
Safe to drive? NO if CEL is flashing. YES with caution if solid, but repair this week.
Estimated repair cost: $20 - $100
Most common causes:
- 1. Worn TPS with dead spots (35-45% of cases)
- 2. Throttle body carbon buildup (10-25% of cases)
- 3. Loose TPS connector (10-25% of cases)
- 4. Damaged throttle linkage (5-10% of cases)
Symptoms
- ⚠️Intermittent power loss
- ⚠️Rough acceleration
- ⚠️Surging at cruise speed
- ⚠️Reduced power mode
Common Causes
How to Diagnose P0121
- 1Watch TPS voltage on scan tool while slowly opening throttle — look for jumps or dropouts
- 2Clean throttle body
- 3Check TPS mounting and connector
- 4Replace TPS if readings are erratic
OEM Procedures for P0121
Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Found 9 OEM service manual procedures.
Remove/Install/Overhaul - Removal (Tracker)
Remove/Install/Overhaul - Removal (Tracker)
Remove/Install/Overhaul - Removal (Tracker)
Remove/Install/Overhaul - Removal (Tracker)
Remove/Install/Overhaul - Removal (Tracker)
Remove/Install/Overhaul - Removal (Tracker)
Replacement - Replace Throttle Position Sensor
Replacement - Replace Throttle Position Sensor
Showing 8 of 9 procedures
OEM Diagnostic Flowchart
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Parts & Tools for This Job
Common parts shoppers buy for P0121 Throttle Position Sensor A Range/Performance.
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OBD2 scanner
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Check SpecificationsBattery tester
Check cranking and charging health before replacing expensive parts.
A weak battery can mimic alternator or starter problems.
Check SpecificationsMultimeter kit
Confirm voltage, continuity, and sensor power with one simple kit.
A meter is the cheapest way to rule out a bad circuit fast.
Check SpecificationsRelated Resources
Repair guides, symptom pages, and wiring diagrams related to P0121.
OEM Manual Evidence
Browse →Diagnostic Trouble Codes (DTC) Index — 2013 Audi A3 Premium, 2.0L Eng VIN E, Automatic DCT Trans Service Manual ~ LEMON Manuals LEMON Manua...
Diagnostic Trouble Codes (DTC) Index — 2013 Audi A3 Premium, 2.0L Eng VIN E, Automatic DCT Trans Service Manual ~ LEMON Manuals LEMON Manua...
Diagnostic Trouble Codes (DTC) Index — 2013 Audi A3 Premium, 2.0L Eng VIN E, Standard Trans Service Manual ~ LEMON Manuals LEMON Manuals: R...
Diagnostic Trouble Codes (DTC) Index — 2013 Audi A3 Premium, 2.0L Eng VIN E, Standard Trans Service Manual ~ LEMON Manuals LEMON Manuals: R...
Exact Vehicle Hubs
Browse →Open the exact vehicle hub grounded by OEM manual evidence related to P0121.
Open the exact vehicle hub grounded by OEM manual evidence related to P0121.
Related Codes
General fault in the TPS circuit. The TPS tells the ECM how far the throttle is open.
TPS voltage is below minimum threshold. The ECM cannot determine throttle position accurately.
TPS voltage is above maximum expected. ECM sees the throttle as more open than it actually is.
Frequently Asked Questions
- How do I test a TPS?
- Using a scan tool, slowly open the throttle from closed to wide open. Voltage should rise smoothly from ~0.5V to ~4.5V with no jumps or drops.
- Can I just clean the throttle body?
- Sometimes cleaning fixes P0121 if carbon is preventing smooth throttle movement. Try cleaning first before replacing the TPS.
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Author & Review
Published by AllOEMManuals, founded by Lyndon Bedford, an automotive technician with 20 years of experience. He owned and operated a mechanic shop in Hurst, Texas from 2014 to 2022 and continues hands-on repair work.
Content may combine manual references, general repair templates, and AI-assisted drafting. Confirm the source, vehicle configuration, and applicability before working. Report corrections through our contact page.
Last updated: 2026-10-29