P0390: Bank 2 exhaust cam circuit monitoring is an event-pattern check

Ford assigns P0390 to the bank 2 exhaust cam-position circuit. Its ignition-system monitor evaluates cam information against engine-position events, which makes the engine's signal pattern important to the diagnosis.

The expected ratio is not universal

The summary lists several engine-position-to-cam-event ratios according to cylinder count. A waveform or event count must therefore be compared with the correct engine configuration. The code does not imply that any single ratio or pulse shape applies across all Ford gasoline engines.

The documented check is continuous with a 200 rpm entry condition and a monitoring duration below five seconds. Retain the crank reference and exhaust-cam evidence together, rather than interpreting a cam signal in isolation.

Separate circuit validity from timing response

The table lists P0394 separately for intermittent bank 2 exhaust cam behavior, where an event appears in an unexpected position. Variable cam timing target-error monitors are also separate. P0390 alone consequently does not establish a phaser response failure or a particular amount of mechanical timing error.

Use the full DTC and the actual engine's circuit and waveform procedure to identify the failed relationship. A displayed exhaust-cam angle can provide context, but cannot replace verification of the signal pattern. The cited summary does not determine a physical sensor location, connector pinout or replacement component. A meaningful post-repair result is a correctly completed cam signal check under valid operating conditions.

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 132.