P128C Code: Meaning, Causes, and Symptoms | OBD2 Codes

P128C – Fuel Rail Temperature Sensor 1 Signal Message Counter Incorrect

 

P128C Possible Symptoms

 

Engine Light ON (or Service Engine Soon Warning Light)

 

P128C Possible Causes

 

Faulty Fuel Rail Temperature Sensor 1,Fuel Rail Temperature Sensor 1 harness is open or shorted,Fuel Rail Temperature Sensor 1 circuit poor electrical connection

 

P128C Description

 

The fuel rail pressure sensor transmits fuel pressure and temperature information by serial data. The fuel rail pressure sensor internal microprocessor allows 4 separate sensor outputs from one 3 wire sensor. The Engine Control Module (ECM) supplies the fuel rail pressure sensor with a 5 V reference circuit, a low reference circuit, and an asynchronous signal/serial data circuit. The asynchronous signal means communication is only going from the fuel rail pressure sensor to the ECM. The ECM decodes the serial data signal into separate voltages which are displayed on a scan tool as the voltage inputs from the Fuel Temperature Sensor, Fuel Rail Pressure Sensor and Fuel Rail Pressure Sensor 2.