P04E8 code meaning
EGR Temperature Sensor D Circuit High
Powertrain system Generic code P04xx codes Check engine light
What P04E8 means
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.
P04E8 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P04E8
- Check engine light on
- Usually no change in driving
- EGR possibly reduced, higher NOx
Common causes of P04E8
- Most likelyConnector off or loose, or pin corroded
- PossibleSensor open internally (heat damage)
- PossibleSensor ground line open
- Less likelySignal line shorted to positive
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR temperature sensor dSensor wiringEngine control module
What each part of P04E8 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| E8 | The exact fault in that area. |
What to do next
- Note P04E8 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P04E8
What does P04E8 mean?
P04E8 means "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. It is a generic code, so it means the same on every make.
Is it safe to drive with P04E8?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P04E8 fail an emissions test?
Yes, it can. P04E8 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P04E8 to fix?
Difficulty: medium. A typical repair takes 0.5 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P04E8 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.