Diagnostic Overview - ESIM Switch Stuck Closed (P0452) Diagnostic
ESIM SWITCH STUCK CLOSED MONITOR: At ignition off, the state of the ESIM Switch is evaluated. If the switch is open, a pass flag will set so the PCM power down process can complete. If the switch is closed, the PCM will wait a calibrated delay time and open the OBD Vent Valve. In a normally functioning system, this will relieve the vacuum trapped in the Charcoal Canister allowing the switch to open. When the switch opens, a pass flag is set and the PCM will power down. If the ESIM switch does not open, after a calibrated time, an error is detected and a switch stuck closed failure event is set (P0452) . Two consecutive failed events will mature a fault. The Switch stuck closed fault can set because of an electrical or mechanical issue. The electrical failures could be a short low in the ESIM signal or the switch is stuck closed inside the ESIM. NOTE: An open signal would cause it to be high and never read closed which would set one of the leak faults. The mechanical failures could be a blockage somewhere in the purge circuit that is not allowing vacuum to be relieved when the OBD Vent Valve is energized. The best way to diagnose the issue is to first determine if the issue is due to an electrical issue or mechanical issue (blockage).
Diagnosing the system for an electrical or mechanical issue:
- First, remove the Fuel Cap or open the Capless fuel filler using a funnel while monitoring the ESIM Switch state. The switch state should change to open. If it does the likely cause is a blockage in the Purge Tube or OBD Vent Valve that is not opening. The reason the switch was able to open when removing the Fuel Cap or opening the capless fuel filler is because this is a different path to atmosphere than the system uses during the diagnostic (refer to the generic graphic below to see this). This also shows that the ESIM Switch is not stuck closed and the signal is not shorted.
- If the ESIM Switch did not open when venting the system to atmosphere it is likely due to a stuck switch or signal circuit shorted low. If the vehicle is equipped with a fuel tank pressure sensor, monitoring the sensor reading can confirm. The Fuel Tank pressure should read near 0 Pa with the system vented. If the tank pressure is near 0 Pa and the switch is reading closed, there is an electrical issue with the switch or wiring.
- Monitor the ESIM Switch state and disconnect the ESIM harness connector. Try not to disturb the wiring harness so that you don't incidentally disturb a wiring issue. If the switch state changes to open when unplugged, a wiring issue can likely be ruled out since an open signal circuit should cause the switch state to change to open. If the switch state still reads closed with the ESIM connector unplugged the signal circuit is shorted low.
| EVAP SYSTEM COMPONENTS | |||
|---|---|---|---|
| CALLOUT | DESCRIPTION | CALLOUT | DESCRIPTION |
| 1 | Filter - Fresh Air Inlet | 15 | Multi-Function Control Valve (MFCV) in the Fuel Delivery Flange |
| 2 | Filter Hose (Filter to ESIM) | 16 | Fuel Tank |
| 3 | Evaporative System Integrity Monitor (ESIM) | 17 | Purge Tube (Purge Solenoid to Canister) |
| 4 | Evaporative Canister | 18 | OBD Vent Valve Tee |
| 5 | Gas Cap or Cap-less Refueling Unit (if equipped) | 19 | OBD Vent Valve |
| 6 | Recirculation Tube (metal portion) (FTPS to Fuel Filler Tube) | 20 | OBD Vent Valve Filter |
| 7 | Fuel Filler Tube | 21 | Purge Solenoid |
| 8 | Fuel Tank Pressure Sensor (FTPS) | 22 | Evaporative System Turbocharger Tee |
| 9 | Grade Vent Valve (GVV) | 23 | Check Valve 2 (to the Turbocharger) |
| 10 | Hose - Fuel Filler Tube to ICV | 24 | Check Valve 1 (to the Manifold) |
| 11 | Inlet Check Valve (ICV) | 25 | Ejector Tee (Venturi) |
| 12 | GVV Tube (GVV to MFCV) | 26 | Hose to the Airbox Side of the Turbocharger |
| 13 | Recirculation Tube (Fuel Tank to FTPS) | 27 | Hose to the Charge Air Cooler Side of the Turbocharger |
| 14 | Canister Tube (Fuel Tank to Canister) | 28 | Manifold Hose (Purge Solenoid to Engine Manifold) |