What Does P042E Mean?
The PCM has detected that the Exhaust Gas Recirculation (EGR) valve 'A' is stuck in the open position. This means exhaust gas is being continuously recirculated into the intake manifold even when not commanded, causing rough idle, stalling, poor acceleration, and potential misfires. The driver will likely notice significant driveability issues, especially at idle.
Common Causes
40%
Carbon buildup preventing the EGR valve from closing fully
30%
Failed EGR valve (mechanical failure, diaphragm rupture, or stuck pintle)
15%
EGR valve actuator/solenoid failure holding valve open
10%
Vacuum line damage routing constant vacuum to the EGR valve (vacuum-operated systems)
5%
PCM driver circuit fault commanding valve open continuously
Diagnostic Steps
1
Monitor EGR commanded position vs. actual position on the scan tool at idle — the commanded position should be 0% at idle; if actual position shows significant opening, the valve is physically stuck.
2
Remove the EGR valve and visually inspect the pintle and seat for carbon buildup — heavy deposits can prevent full closure. Clean with carburetor cleaner and a wire brush if carbon is present.
3
With the EGR valve removed, apply vacuum (vacuum-operated) or 12V command signal (electronic) and verify the valve opens and closes freely and seats completely.
4
On electronic EGR valves, backprobe the control circuit and verify the PCM is commanding the valve closed (0% duty cycle) at idle — if commanding closed but valve stays open, the valve has failed.
5
Check for vacuum leaks in the EGR vacuum supply line (vacuum-operated systems) that could hold the valve open.
Estimated Repair Cost
$150 - $550
Parts + labor, varies by vehicle and location
The PCM has detected that the Exhaust Gas Recirculation (EGR) valve 'A' is stuck in the open position. This means exhaust gas is being continuously recirculated into the intake manifold even when not commanded, causing rough idle, stalling, poor acceleration, and potential misfires. The driver will ...
The most common cause of P042E (Exhaust Gas Recirculation "A" Control Stuck Open) is: Carbon buildup preventing the EGR valve from closing fully
Typical repair costs for P042E range from $150 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Drive with caution. A stuck-open EGR valve can cause stalling at intersections, rough idle, and significant power loss. If the vehicle stalls or runs very poorly, avoid highway driving until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P042E to identify the root cause.
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Quick Info
Category
Powertrain
System
Exhaust Gas Recirculation (EGR)
Difficulty
Type
Generic (SAE)
Recommended Tools
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