P04E9 EGR Temperature Sensor D Circuit Intermittent/Erratic

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. P04E9 means the signal briefly leaves its valid range or changes impossibly fast – typically a loose contact. Ford detects such sporadic faults on other sensors with short limit violations of about 0.4 s.

Likely causes

Symptoms

• Check engine light on, may come and go
• Usually no change in driving

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.