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C2121 fault code: what it means

C2121: TPMS transmitter ID 1 not received on a Lexus: one tyre sensor is not being heard. TPMS light on.

Chassis (brakes, steering, suspension) · Keep an eye on

Usual causes, most likely first

  1. flat or failed sensor battery
  2. sensor damaged at tyre change
  3. IDs not registered after wheel swap

C2121 by make

Lexus

TPMS transmitter ID 1 not received on a Lexus: one tyre sensor is not being heard. TPMS light on.

Usual causes: flat or failed sensor battery; sensor damaged at tyre change; IDs not registered after wheel swap

Toyota

TPMS transmitter ID 1 not received: the tyre pressure receiver is not hearing from one tyre sensor. TPMS light on.

Usual causes: flat or failed sensor battery; sensor damaged at tyre change; sensor IDs not registered after wheel swap

Not sure what C2121 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.