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DTC codes / P06xx · Computer and output circuits / P06FF

P06FFEconomy Mode Lamp Control Circuit

P06FF indicates that the powertrain control module has detected a fault in the electrical circuit that controls the economy mode indicator lamp, which is the light that confirms when the vehicle has entered its fuel-saving operating strategy. The computer monitors the lamp control circuit for abnormal voltage or current and sets this code when the circuit does not behave as expected during the lamp's on or off command.

SystemPowertrain
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • The economy mode indicator lamp fails to illuminate when the mode is activated
  • The economy mode lamp stays on continuously regardless of the mode selected
  • The driver may notice no change in vehicle performance or fuel economy
  • Often no symptoms besides the warning light on the dashboard
  • Other dashboard warning lights may illuminate if the fault affects shared circuitry
  • The economy mode may not engage or may disengage unexpectedly

Common causes, most likely first

  1. Failed economy mode indicator bulb or light-emitting diode assembly
  2. Open or shorted wiring in the lamp control circuit
  3. Corroded or loose electrical connector at the lamp or control module
  4. Faulty economy mode switch or mode selector button
  5. Internal failure in the body control module or powertrain control module driver circuit
  6. Blown fuse that supplies power to the lamp circuit
  7. Water intrusion or physical damage to the lamp housing or harness

How to diagnose and fix it

  1. Verify the condition by commanding the economy mode lamp on and off with a scan tool and observing whether the lamp responds
  2. Check the fuse that protects the lamp circuit and replace it if blown, then recheck for the code
  3. Inspect the lamp bulb or light-emitting diode and replace it if faulty, confirming the connector is clean and tight
  4. Disconnect the lamp connector and measure voltage and ground at the terminals while commanding the lamp on to isolate a wiring fault
  5. Perform a continuity and resistance test on the control circuit between the lamp and the control module to find opens or shorts
  6. Test the economy mode switch for proper operation and replace it if it does not change state correctly
  7. If all external circuits and components test good, diagnose the control module driver circuit and replace the module only after confirming the fault is internal

What the economy mode lamp circuit really tells you

  • A burned-out economy mode indicator bulb is the most common cause of this code, yet many technicians replace the control module first because they skip the simple bulb check.
  • The code can set even when the economy mode itself functions perfectly, because the lamp circuit is monitored separately from the mode activation logic.
  • On some vehicles the economy mode lamp shares a ground or power feed with other dashboard indicators, so a fault in a neighbouring circuit can trigger P06FF alongside other codes.
  • Aftermarket LED bulb replacements can draw too little current for the control module to detect, causing a false P06FF even though the lamp appears to work.
  • A weak or failing battery can cause intermittent lamp circuit faults that set P06FF only during cranking or low-voltage conditions.

Can I keep driving with P06FF?

This code does not affect engine operation or safety, so you can continue driving normally while you arrange diagnosis and repair. Avoid ignoring the warning light indefinitely, because a related wiring fault could eventually affect other dashboard indicators or the economy mode function itself.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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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