TPS has intermittent open or short internally; Harness is rubbing and causing an open or short in the wiring; Bad connection at the TPS; Bad PCM (less likely); Water or corrosion in connector or sensor

Read the code and freeze-frame data with an OBD-II scanner; Check the connector and wiring of the part named in the code; Test the part with scanner live data or a multimeter, using the values in the repair manual; Fix the cause, clear the code and test-drive

P0121 on Honda City GM2: Throttle Position Sensor A Circuit Range/Performance

Short answer: P0121 means “Throttle Position Sensor A Circuit Range/Performance”. The car’s computer has found a fault in the Engine system and turns on the Check engine light (MIL). First check: read the code and freeze-frame data with an OBD-II scanner.

Standard OBD-II code Same meaning on all cars (SAE J2012). Not checked against this car’s factory manual.

Code: P0121
System: Engine
Dashboard light: Check engine light (MIL)
Applies to: Generic OBD-II meaning. Not every code is used by this car.
Confidence: medium (generic OBD-II definition, not checked against the factory manual for this car)
Source: obd-codes.com

Symptoms and when it is set

Check engine light on

Likely causes

TPS has intermittent open or short internally
Harness is rubbing and causing an open or short in the wiring
Bad connection at the TPS
Bad PCM (less likely)
Water or corrosion in connector or sensor

What to check, in order

Read the code and freeze-frame data with an OBD-II scanner
Check the connector and wiring of the part named in the code
Test the part with scanner live data or a multimeter, using the values in the repair manual
Fix the cause, clear the code and test-drive

Related on this car

Same code on other cars

← P0120 P0122 →

Clearing the code does not fix the fault. If it comes back, the problem is still there. For brakes, airbags and steering, see a trained mechanic.