Possible Causes of P128D Code
- Faulty fuel rail temperature sensor 2
- Fuel rail temperature sensor 2 harness is open or shorted
- Fuel rail temperature sensor 2 circuit poor electrical connection
How is P128D Code Repair Performed?
Begin by checking the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
What are the Possible Symptoms of P128D Code?
- Engine Light ON (or Service Engine Soon Warning Light)
What Does P128D Code Mean?
The fuel rail pressure sensor transmits fuel pressure and temperature information via serial data. The internal microprocessor of the fuel rail pressure sensor enables 4 separate sensor outputs from a 3-wire sensor. The Engine Control Module (ECM) supplies the fuel rail pressure sensor with a 5V reference circuit, a low reference circuit, and an asynchronous/serial data signal circuit. The asynchronous signal means communication only goes from the fuel rail pressure sensor to the ECM. The ECM decodes the serial data signal into separate voltages that are displayed on a scan tool as fuel temperature sensor, fuel rail pressure sensor, and fuel rail pressure sensor 2 voltage inputs.