P042E on 2007-2024 RAM 2500 (2500 6.7L Cummins) — Exhaust Gas Recirculation "A" Control Stuck Open
1 vehicles · 1 makes · $500-$1,800 repair
Most Reported On
P042E is an OBD-II diagnostic trouble code meaning “Exhaust Gas Recirculation "A" Control Stuck Open.” P042E is a generic (SAE-standard) OBD-II powertrain code set when the powertrain control module determines the EGR "A" control valve is stuck in the open position — commanded flow does not drop to the expected level when the PCM commands the valve closed. With EGR flowing when it shouldn't, exhaust gas dilutes the intake charge at idle and low load. Drivers typically see a check engine light plus rough or unstable idle, hesitation, stalling on deceleration, and a failed emissions test. This code is most commonly reported on 2007-2024 RAM 2500 (2500 6.7L Cummins), with repair costs ranging from $500 to $1,800.
Common Causes
Typical Repair Cost
Based on 1 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
This is a powertrain code, so a basic OBD-II reader can read it. These read P042E.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple code reader for engine (P) codes on many compatible OBD-II vehicles. It does not support every vehicle or hybrid/EV application, and it does NOT read body, chassis or network codes; confirm exact-vehicle compatibility before buying.
- Read & clear engine (P) codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth scanner with a companion app that reads beyond the engine module — ABS, SRS and transmission — plus manufacturer-specific codes on many vehicles.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X V3.0 Elite OBD-II Scanner
by LAUNCH
Handheld scanner covering the four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level tablet with all-system coverage and bi-directional control, so you can command a module rather than only read it.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
What you can do yourself, and what needs a shop
Reading the code, clearing it, and watching whether it returns is a driveway job with the right scanner. These steps are not:
- Module programming or software updates — needs the manufacturer software or a J2534 pass-through with a paid subscription.
- Replacing a control module — most are VIN-programmed and immobilizer-registered, so a new one does nothing until it is coded to your car.
- Airbag/SRS component work — a stored fault can deploy a live device.
If the vehicle is still under warranty, check for an open recall or technical service bulletin before buying anything — the repair may already be covered.
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FAQ
What does P042E mean?
P042E stands for "Exhaust Gas Recirculation "A" Control Stuck Open." P042E is a generic (SAE-standard) OBD-II powertrain code set when the powertrain control module determines the EGR "A" control valve is stuck in the open position — commanded flow does not drop to the expected level when the PCM commands the valve closed. With EGR flowing when it shouldn't, exhaust gas dilutes the intake charge at idle and low load. Drivers typically see a check engine light plus rough or unstable idle, hesitation, stalling on deceleration, and a failed emissions test.
What are the most common causes of P042E?
The most common causes of P042E are: EGR valve carboned up or stuck open by soot deposits, Failed EGR valve or its internal position sensor, Clogged or partially blocked EGR passages and cooler, Wiring, connector, or ground fault in the EGR valve control circuit, Vacuum leak or stuck vacuum solenoid on vacuum-actuated EGR systems, PCM software/calibration issue or, rarely, a failed PCM driver. The specific cause varies by vehicle.
How much does it cost to fix P042E?
Repair costs for P042E range from $500 to $1,800, depending on the vehicle and root cause.
Which vehicles are affected by P042E?
Au7o has documented P042E across 1 vehicle models from 1 manufacturers: RAM.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.