P0121 on Honda vehicles
Throttle Position Sensor Range / Performance — what it means on a Honda, whether it's safe to drive, and the fixes by model and year.
P0121 on a Honda means throttle position sensor range / performance. Most vehicles stay drivable short-term, but diagnose it promptly. The most common cause is worn throttle position sensor (mechanical tps wear) (typically $100–$400). Pick your Honda model below for its known failure patterns, recalls, and TSBs.
What does P0121 mean on a Honda?
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.
P0121 is a standardized OBD-II code, so its definition is the same on every Honda. What differs by model and engine is which cause is most likely — pick your Honda model below for a diagnosis tuned to its known failure patterns, recalls, and TSBs.
Is it safe to drive a Honda with P0121?
In most cases a Honda 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. Exact tolerance depends on the model and engine.
What causes P0121 on a Honda?
| 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 |
Repair costs are typical US ranges and vary by Honda model, model year, and labor rate. A diagnostic trouble code is a symptom, not a guaranteed failed part — confirm the root cause before replacing anything.
P0121 by Honda model
Select your Honda model and year for a P0121 diagnosis tuned to that vehicle's failure patterns, recalls, and TSBs.
Honda CR-V
2,324 NHTSA owner complaints · 13 recalls on record across the years covered below.
Honda Civic
1,894 NHTSA owner complaints · 13 recalls on record across the years covered below.
Honda Accord
1,078 NHTSA owner complaints · 15 recalls on record across the years covered below.
Honda Pilot
1,176 NHTSA owner complaints · 16 recalls on record across the years covered below.
Honda HR-V
191 NHTSA owner complaints · 3 recalls on record across the years covered below.
Honda Odyssey
402 NHTSA owner complaints · 16 recalls on record across the years covered below.
Complaint and recall counts are NHTSA totals for the model years covered on this site, not counts specific to P0121.
P0121 on other makes
Other codes on Honda vehicles
P0121 on a Honda: frequently asked questions
What does diagnostic trouble code P0121 mean on a Honda?
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. P0121 is a standardized OBD-II code, so the definition is the same on every Honda — which cause is most likely varies by model and engine.
What are the symptoms of P0121 on a Honda?
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 Honda?
Worn throttle position sensor (mechanical TPS wear) (most-common). Carbon buildup in the throttle body causing the blade to bind (common). Corroded TPS connector or damaged signal wiring (common). Failed electronic throttle body (combined ETB / TPS unit) (common). TPS sensor needs reset / relearn after battery disconnect (occasional). Damaged accelerator pedal position sensor (separate code in some cases) (occasional). PCM input fault (rare) (rare)
Is it safe to drive a Honda with P0121?
In most cases a Honda stays drivable for short trips with P0121 active, but it should be diagnosed and repaired promptly — this is a high-severity code. Ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on the model and engine.