P04E8 EGR Temperature Sensor D Circuit High

Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. Sensor D is the fourth of up to four EGR temperature sensors, conceivable on engines with high- and low-pressure EGR and a sensor before and after each cooler; it is usually an NTC whose low voltage means hot. No manufacturer document available to us uses sensor D; the description follows CARB and Ford's checks on sensor B as a comparison. P04E8 means the signal is above its upper limit – an open circuit in sensor, connector, line or ground, or a short to positive; the reading looks very cold. For sensor B Ford uses above 4.95 V. A substitute value is used.

Likely causes

Symptoms

• Check engine light on
• Usually no change in driving
• EGR possibly reduced, higher NOx

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, fordservicecontent.com.