X80 - Code 542: Does Engine Start

Diagnostic Trouble Code (DTC) 542 indicates that one of the following has occurred:

No Start:
- Inertia Fuel Shutoff (IFS) switch not reset or electrically open (if in secondary circuit).
- Open circuit between the fuel pump and Fuel Pump Monitor (FPM) circuit connection to power-to-pump circuit.
- Poor fuel pump ground.
- Fuel pump electrically open.

Engine Starts:
- Fuel pump secondary circuit short to power.
- Fuel pump relay contacts always closed.
- Open in FPM circuit between Powertrain Control Module (PCM) and connection to power-to-pump circuit.
- Left/Front Heated Oxygen Sensor (HO2S) short to power (dual HO2S applications).
- Damaged PCM.

- Does the engine start?

Yes -- Go to X81. X81 - Verify Fuel Pump Is Off

No -- Go to X85. X85 - Check Inertia Fuel Shutoff Switch