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DTC codes / P20xx · Fuel and air metering and auxiliary emission controls / P20D7

P20D7Exhaust Aftertreatment Fuel Supply Control Circuit/Open

P20D7 indicates that the powertrain control module (PCM) has detected an open circuit in the exhaust aftertreatment fuel supply control circuit, which is responsible for delivering diesel fuel to the exhaust system for regeneration of the diesel particulate filter (DPF). The PCM monitors the circuit for expected voltage or current and sets this code when the signal is missing or out of range, indicating a break in the wiring or a failed component.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp, MIL), often with no other symptoms
  • Reduced engine power or limp mode due to the PCM limiting torque to protect the aftertreatment system
  • Frequent active regeneration attempts or a regeneration that never completes, leading to soot accumulation
  • A noticeable decrease in fuel economy as the engine compensates for incomplete regeneration
  • Possible black smoke from the tailpipe if the DPF becomes overloaded
  • A stored pending code or history code for the same circuit, sometimes accompanied by other aftertreatment codes

Common causes, most likely first

  1. Open or damaged wiring in the fuel supply control circuit, such as a broken wire, corroded connector, or chafed harness
  2. Failed fuel supply control solenoid or actuator that has an open coil
  3. Blown fuse or faulty relay that supplies power to the fuel supply control circuit
  4. Poor electrical connection at the PCM or at the fuel supply control module, including loose pins or water intrusion
  5. Internal PCM fault, though this is less common and should be confirmed after all other possibilities are ruled out
  6. Aftermarket accessories or improper previous repairs that have disturbed the circuit

How to diagnose and fix it

  1. Perform a visual inspection of the fuel supply control circuit wiring and connectors for damage, corrosion, or loose pins
  2. Check the fuse and relay that provide power to the fuel supply control circuit and replace if faulty
  3. Use a digital multimeter to measure resistance across the fuel supply control solenoid or actuator; compare to manufacturer specifications
  4. Backprobe the PCM connector and check for voltage or ground signals on the control circuit while commanding the component on with a scan tool
  5. Perform a voltage drop test on the power and ground sides of the circuit to identify excessive resistance
  6. If the circuit and component test good, check for technical service bulletins (TSBs) or known issues for the specific vehicle make and model
  7. If all else fails, substitute a known-good PCM and retest, ensuring proper programming and relearn procedures

Don't overlook the fuel supply control circuit

  • A common mistake is to replace the fuel supply control solenoid without first checking the wiring harness for an open circuit, which is often the real culprit.
  • The code can be set by a faulty fuel supply control module that is separate from the PCM, so testing both ends of the circuit is essential.
  • In some vehicles, the fuel supply control circuit is shared with other aftertreatment components, so an open in a common power or ground can set multiple codes.
  • A scan tool that can command the fuel supply control actuator on and off is invaluable for verifying whether the circuit can carry current under load.
  • Even after repairing the open circuit, the PCM may require a relearn or a forced regeneration to clear the code and restore normal operation.

Can I keep driving with P20D7?

You can usually drive the vehicle to a repair shop, but avoid heavy loads and long trips because the aftertreatment system may not regenerate properly, leading to increased emissions and potential damage to the diesel particulate filter. If the engine enters limp mode, limit driving to essential trips and seek service promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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