P04D1 code meaning
EGR Temperature Sensor C Circuit High
Powertrain system Generic code P04xx codes Check engine light
What P04D1 means
Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. The code standard allows up to four EGR temperature sensors, A to D – for example before and after the cooler, or in the high- and low-pressure circuits; which is which depends on the maker. Sensor C is the third of them, usually an NTC whose low voltage means hot. P04D1 means its signal voltage is above the upper limit – extremely cold, or more often an open sensor, signal or ground line, or a short to 5 V. Besides FCA, GM documents it on the 3.0-litre Duramax LM2 of 2020–21, where it is called EGR temperature sensor 2; if the diagnosis leads to the engine module, module and sensor are replaced together. For sensor B Ford diesels use above 4.95 V.
P04D1 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 P04D1
- Check engine light on
- Usually no change in driving (EGR on a substitute value or off)
- Possibly EGR flow or cooler codes (P0401, P2457)
Common causes of P04D1
- Most likelySignal or ground line open, connector off or corroded
- PossibleSensor open internally (element broken)
- Less likelySignal shorted to 5 V or positive
- Less likelyEngine module input
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR temperature sensor cSensor wiringEngine control module
What each part of P04D1 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). |
| D1 | The exact fault in that area. |
What to do next
- Note P04D1 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 P04D1
What does P04D1 mean?
P04D1 means "EGR Temperature Sensor C 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 P04D1?
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 P04D1 fail an emissions test?
Yes, it can. P04D1 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 P04D1 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 P04D1 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.