P04E6: EGR Temperature Sensor D Circuit Range/Performance

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. P04E6 means the signal is electrically valid but implausible – for example it differs from other temperatures after a long stop, does not react when EGR opens, or freezes. Ford compares sensor B with intake and charge air after at least 6 hours off and flags more than 25 °C.

Medium severity. Can I keep driving?You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

Symptoms

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

Most likely causes

Sensor drifting (soot or oil crust, ageing)
Contact resistance in connector or harness (heat, corrosion)
Real temperature deviation: EGR cooler or bypass faulty, valve sticking
Comparison sensor faulty

What to check, in order

Start with the simplest. You can tick off each step.

Check the connector and any vacuum hoses
Compare the reading with other engine data while varying the engine speed.
Use live data to compare the commanded opening with the actual opening
Clean the valve and passages if they are clogged with carbon
Test the actuator with the scanner
Replace the valve if it still does not follow the command after cleaning

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P04E6 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
4: Emissions
E6: Specific fault in that system

Frequently asked questions

Can I keep driving with code P04E6?

You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

What causes code P04E6?

The most common causes are: sensor drifting (soot or oil crust, ageing); contact resistance in connector or harness (heat, corrosion); real temperature deviation: EGR cooler or bypass faulty, valve sticking.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.