Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Exhaust Gas Recirculation (EGR) Cooler System Monitor - Transit
The functionality of the EGR cooler system, including the EGR cooler bypass valve and the exhaust gas temperature bank 1 sensor 2 (EGRT12), is monitored by comparing the measured EGR gas temperature downstream of the EGR cooler assembly, with the measured engine coolant temperature when certain engine operating conditions exist. The operating conditions in which this detection can occur are the monitor entry conditions. Changes in engine operating conditions cause a delay before the changes are reflected in the EGR cooling system temperatures. The entry conditions timers must complete before the monitor is complete. When a condition feeding a timer is no longer met, the timer resets. Excessive EGR cooling and insufficient EGR cooling can be detected using the EGR cooler bypass monitor.
The insufficient EGR cooling monitor detects when the EGR is being cooled less than desired, such as when the EGR cooler bypass is stuck in the bypass position. The entry conditions for the insufficient EGR cooling monitor must be met for the monitor to be enabled. Once the entry conditions are met and while they continue to be met, the measured exhaust gas temperature downstream of the EGR cooler assembly is compared to a threshold based on measured engine coolant temperature. A typical value for this threshold is 150° C (270° F) above engine coolant temperature. If the measured exhaust gas temperature downstream of the EGR cooler assembly is greater than the threshold, for a predetermined amount of time, a DTC is set.
The excessive EGR cooling monitor can detect when EGR is being cooled greater than desired, such as when the EGR cooler bypass is stuck in the cooling position. The entry conditions for the excessive EGR cooling monitor must be met for the monitor to be enabled. Once the entry conditions are met and while they continue to be met, the measured exhaust gas temperature downstream of the EGR cooler assembly is compared to a threshold based on measured engine coolant temperature. A typical value for this threshold is 30° C (54° F) above engine coolant temperature. If the measured exhaust gas temperature downstream of the EGR cooler assembly is less than the threshold, for a predetermined amount of time, a DTC is set.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.