P204E code meaning
Reductant Pressure Sensor Circuit Intermittent/Erratic
Powertrain system Generic code P20xx codes Check engine light
What P204E means
P204E covers a DEF pressure signal that jumps around although it stays inside the electrical limits, as with a loose terminal, a cracked wire or a sensor with an internal contact problem. GM's 2025 DEF controller is the public calibration: it adds up all absolute pressure changes over a moving window of 100 readings taken every 10 ms and counts a failure when that sum passes 1500 kPa while pumping forward, 1000 kPa when stopped or heating, or 200 kPa in reverse; ten failures within 100 runs store a Type A code. No other manufacturer documents the code in public. CARB expects input components to be checked for implausible as well as out-of-range signals. Besides the wiring, air in the line or a pump delivering unevenly can also make the pressure swing.
P204E at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P204E
- MIL on, fault may come and go
- Dosing interrupted at times
- Accompanying DEF pump or pressure codes
Common causes of P204E
- Most likelyLoose or fretted terminal at the pressure sensor connector
- PossibleWire breaking intermittently under vibration
- PossibleAir in the DEF line or uneven pump delivery
- Less likelyPressure sensor with internal intermittent fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant pressure sensor
What each part of P204E means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| 4E | The exact fault in that area. |
What to do next
- Note P204E 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 P204E
What does P204E mean?
P204E means "Reductant Pressure Sensor Circuit Intermittent/Erratic". P204E covers a DEF pressure signal that jumps around although it stays inside the electrical limits, as with a loose terminal, a cracked wire or a sensor with an internal contact problem. It is a generic code, so it means the same on every make.
Is it safe to drive with P204E?
Drive gently and only to a workshop. With P204E the car can go into limp mode (reduced power) to protect itself.
Will P204E fail an emissions test?
Yes, it can. P204E 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 P204E to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P204E clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.