EGR Cooler Efficiency Below Threshold

What this code means

The EGR cooler is not reducing exhaust gas temperature sufficiently. This can indicate an internal leak or coolant passage blockage.

Symptoms

• Check Engine Light
• Elevated intake manifold temperature
• Increased NOx emissions
• Coolant level dropping slowly
• White smoke from exhaust (coolant)
• Sweet smell from exhaust

Common causes

• EGR cooler internal leak
• EGR cooler coolant passage blocked
• EGR cooler fins clogged with soot
• Thermostat affecting coolant temperature
• Insufficient coolant flow through cooler

Diagnostic steps

1. Compare EGR cooler inlet and outlet temperatures
2. Check coolant level and condition
3. Pressure test EGR cooler
4. Inspect exhaust for coolant contamination
5. Monitor coolant consumption

Repair notes

Replace EGR cooler if leaking or if efficiency cannot be restored. An internal leak can cause catastrophic engine damage from hydro-lock.

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