How severe is this DTC?
A stored P20D9 code should be considered severe and addressed as soon as possible. The EAS system may be damaged due to the conditions that contributed to storing the P20D9 code.
What are some of the symptoms of the code?
Symptoms of a P20D9 fault code may include:
- Decreased engine performance
- Excessive black smoke from the vehicle’s 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 supply pump
- Defective EAS fuel pressure sensor
- Open or shorted wiring in the EAS fuel supply control circuit
- Insufficient DEF in the EAS tank
- Faulty EAS controller/PCM or programming error
What are the troubleshooting steps for P20D9?
A diagnostic scanner, digital volt/ohmmeter (DVOM), and vehicle-specific diagnostic information source will be needed to diagnose a P20D9 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 like 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 the 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’s 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 proper power and ground circuits are detected, use the scanner to activate the EAS fuel pump and test the output control circuit voltage. If voltage is insufficient, test the EAS fuel pump relay. If no input voltage is detected, suspect the controller is faulty or encountered a programming error. If input voltage is present at the relay but output voltage is not detected, suspect the relay is bad.
If the EAS power supply voltage output circuit is within parameters, use the DVOM to test the EAS fuel pressure sensor and fuel pump. If either of these components does not meet manufacturer specifications, suspect it has failed.
Remember ground circuits during voltage drop testing