P042E — Exhaust Gas Recirculation Control Stuck Open — 6.7 Cummins (EGR + DPF, pre-SCR)

Diagnostic reference for 6.7L Cummins 2007.5–2012 (EGR + DPF, pre-SCR).

Updated October 15, 2026

What it means

The EGR control circuit reports the valve stuck in the open position.¹

Most likely causes

1. EGR valve stuck mechanically open due to carbon/soot buildup in valve or cooler passages — Valve fails to close; EGR flow remains high when commanded closed.¹²
2. EGR valve position sensor / feedback circuit fault causing ECM to interpret valve as open — Erroneous position feedback makes ECM think valve is stuck open.¹³
3. EGR control circuit wiring or connector issue affecting valve command/feedback — Open/short or corrosion in EGR valve harness leads to stuck-open detection.¹³
4. EGR valve actuator/electrical driver fault — Valve actuator cannot close properly due to electrical fault.¹³

How to diagnose

1. Verify code and freeze frame; confirm P042E is present on 6.7 Cummins 2007.5–2012 EGR+DPF pre-SCR platform.
2. Inspect EGR valve and cooler for carbon/soot buildup that can mechanically hold valve open.
3. Check EGR valve position sensor feedback and related wiring/connector for opens, shorts, or corrosion.
4. Command EGR valve through scan tool and monitor commanded vs actual position; look for failure to close.
5. Inspect EGR control circuit integrity and actuator operation; verify electrical supply and ground to valve.

Common mistake to avoid

Replacing the EGR valve without testing it. If the valve still moves freely, a carbon cleaning often fixes the flow code; and if it opens on command but the code stays, the blockage is in the passages or cooler, not the valve. Source: FleetRabbit — EGR valve problems and repair.

Parts and tools you may need

• Scan tool with bi-directional EGR control
• Digital multimeter
• Inspection light/borescope
• Basic hand tools for EGR valve access

Tools you’ll need

• OBD-II scan tool with bi-directional control — Commands the EGR valve and compares commanded vs actual position to confirm the valve is stuck open on this 6.7 Cummins.
• Digital multimeter — Tests the EGR position sensor feedback circuit and actuator supply/ground for opens, shorts, or corrosion causing a false open reading.
• Borescope — Inspects the EGR valve and cooler passages for carbon/soot buildup that can mechanically hold the valve open without disassembly.

Rough cost and difficulty

Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

If diagnosis is inconclusive or repair involves high-pressure fuel or emissions-critical components, have a qualified diesel technician perform diagnosis and repair.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

Sources