P28F7 code meaning
Exhaust Pressure Too High Bank 1
Powertrain system Generic code P28xx codes Check engine light
What P28F7 means
P28F7 reports that the pressure in the exhaust of bank 1 is higher than the engine model allows. GM documents it in its 2025 diesel ECM tables (25OBDG04B): the monitor looks at the low-pressure EGR differential pressure and fails above 80 kPa while torque demand exceeds a speed-dependent minimum (around 520 Nm at low engine speed, falling to 20 Nm at high speed), counting 480 failures in 600 samples; it is Type A, MIL on the first trip. GM names the cause as an exhaust throttle valve in the wrong position, for example with the link between its upper and lower shafts broken so the plate can stay shut although the actuated shaft has moved. GM bulletin 21-NA-149 lists P28F7 for the 3.0 L LM2 Duramax. Excess back pressure costs power and fuel and stresses the turbocharger.
P28F7 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P28F7
- Check engine light on
- Reduced engine power
- Higher fuel consumption and more frequent filter regenerations
Common causes of P28F7
- Most likelyExhaust throttle valve stuck closed or its shaft linkage broken
- PossibleExhaust restricted downstream, for example by a heavily loaded particulate filter or damaged pipe
- Less likelyChafed engine harness disturbing valve control (GM 21-NA-149)
- Less likelyPressure sensor reading too high without a separate sensor code
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Exhaust pressure control valve aExhaust pressure sensor b1Particulate filterExhaust system
What each part of P28F7 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 8 | Area: transmission. |
| F7 | The exact fault in that area. |
What to do next
- Note P28F7 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 P28F7
What does P28F7 mean?
P28F7 means "Exhaust Pressure Too High Bank 1". P28F7 reports that the pressure in the exhaust of bank 1 is higher than the engine model allows. It is a generic code, so it means the same on every make.
Is it safe to drive with P28F7?
Drive gently and only to a workshop. With P28F7 the car can go into limp mode (reduced power) to protect itself.
Will P28F7 fail an emissions test?
Yes, it can. P28F7 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 P28F7 to fix?
Difficulty: medium. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P28F7 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.