Code Definition

P042E — EGR valve stuck open

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P042E

P042E is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P042E is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P042E is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

This fault code is set when the engine control module (ECM) detects that the EGR valve is stuck in the open position. The ECM monitors the EGR system and expects the valve to close fully when it is not activated. This code is set when the feedback from the EGR position sensor or related sensors indicates that the valve remains open beyond a specific time or under conditions where it should be closed, leading to excessive exhaust gas recirculation.

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