P0121 Toyota Sa Diagnostic Trouble Code

P0121 Toyota Sa code definition:
P0121 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Toyota Sa.

P0121 Toyota Sa is described as Intake Air Temperature (IAT) Circuit Malfunction. It's actually a general trouble code for a problem on IAT electrical circuit sensor, as it sends incorrect voltage input signals to the PCM. If the car doesn't start, they will proceed by testing the voltage at the fuel pump connector and see if the fuel pump relay, fuse, and PCM circuitry should be inspected.

Symptoms

Symptoms of a P0121 Toyota Sa diagnostic trouble code may include:
Place of P0121 in engine

Possible Causes :

  • Defective ECU strategies or components will prevent proper regeneration
  • The Mass Airflow sensor is a hot wire that senses the volume of air entering the intake manifold. The computer uses this information to control fuel mixture.
  • Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)

Common Misdiagnoses

  1. Vehicle Speed Output Circuit Problem
  2. Cruise Control Servo Indicates Low Problem
  3. A/C System High Pressure High Temperature Problem
  4. PCM Stack Overrun Problem
  5. Transmission Control Module Reprogrammable Memory Problem

Repair Processes :

Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. If you find a related TSB, the information will often help in diagnosing the code in question as TSBs are crested from many thousands of repairs.

Process Tips

Diagnostic trouble code P0121 Toyota Sa is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before P0121 Toyota Sa.

Fortunately, P0121 Toyota Sa is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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