How serious is this DTC?
A stored P20DF code should be considered serious and addressed as soon as possible. The EAS system may be damaged due to the conditions that contributed to storing the P20DF code.
What are some symptoms of the code?
Symptoms of a P20DF fault code may include:
- Decreased engine performance
- Excessive black smoke from vehicle exhaust
- Reduced fuel efficiency
- Other EAS/SCR related codes
What are some common causes of the code?
Causes of this code may include:
- Faulty EAS fuel pressure sensor
- Defective EAS fuel supply pump
- Open or shorted wiring in EAS fuel pressure sensor circuit
- Faulty EAS controller/PCM or programming error
What are the troubleshooting steps for P20DF?
A diagnostic scanner, digital volt/ohmmeter (DVOM), and vehicle-specific diagnostic information source will be needed to diagnose a P20DF code.
Finding a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as engine size, stored codes, and presented symptoms, could provide helpful diagnostic information.
I prefer to start my diagnosis with a visual inspection of EAS wiring harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.
I would continue by plugging the scanner into the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Consider noting this information before clearing codes. Test drive the vehicle until the PCM enters readiness mode or the code resets.
If the PCM enters readiness mode at this point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to storing the code may need to worsen before an accurate diagnosis can be made.
If the code immediately resets, to complete the next step of your diagnosis, you’ll need to consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications.
Use the DVOM to test (voltage drop) all grounds in the EAS fuel supply system. Continue by testing the EAS control system power supply. Test fuses with the circuit loaded to avoid misdiagnosis.
If all system fuses are intact, use the DVOM to test the EAS fuel pressure sensor and sensor circuits. If any of these components don’t meet manufacturer specifications, suspect they have failed.
Don’t forget ground circuits during voltage drop testing