P06D5: Reference E uses an internal bandgap check, not the external five-volt limits

P06D5 is Ford's sensor-reference voltage E range/performance result. The cited monitor evaluates a filtered bandgap reference voltage. This is materially different from the external five-volt reference A/B/C/D checks described on the preceding page.

Identify the quantity being evaluated

Ford gives the bandgap bounds as 1.194 and 1.305 volts. Those figures describe the internal monitored reference quantity; they are not a specification to seek at every sensor supply terminal labeled E in another vehicle's documentation.

The check requires the engine to be running with battery voltage in an 11–16-volt window and uses a five-second monitoring duration. An ignition-on measurement made with the engine stopped is therefore not the same enabled state described for this monitor.

Do not transplant another reference diagnosis

The neighboring five-volt circuits use different codes and thresholds. Their short-to-ground or short-to-battery categories cannot simply be applied to the filtered bandgap result. The full P06D5/P06D2_92 identity helps keep the monitored function clear.

Use the matching controller's diagnostic procedure to determine how its internal reference result should be confirmed. The summary does not provide a connector test, a component-level repair or proof that the PCM must be replaced. Verification should establish that the internal reference monitor completes successfully under its stated running and supply conditions, with related sensor or processor faults interpreted in that context.

Source and applicability

This explanation covers the cited Ford monitor variants, not every vehicle displaying this code. Match the engine, sensor architecture and calibration before applying numerical limits.

Ford OBD summary, PDF page 130, Ford OBD summary, PDF page 131.