P2B98 code meaning
Exhaust Pressure Control Valve A Supply Low
Powertrain system Generic code P2Bxx codes Check engine light
What P2B98 means
P2B98 says the motor of exhaust pressure control valve A is not getting enough supply voltage. On GM's 3.0-litre Duramax, whose 2025 table 25OBDG04B documents the code, the H-bridge that drives the exhaust flap reports undervoltage below 6 V; 240 failed out of 300 samples taken every 12.5 ms set it, outside cranking and with the powertrain relay delivering more than 11 V. Type A, MIL after one trip. Because the main relay is fine in that case, the loss lies further on: a fuse, the feed wire, the connector or a weak ground of the driver. GM bulletin 21-NA-149 lists P2B98 among codes that chafed engine harnesses and blown fuses caused on 2019–2021 trucks, the 3.0 l LM2 included. Without power the flap stays put, so warm-up and back-pressure control suffer. P2B99 is the overheating driver.
P2B98 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 P2B98
- Check engine light after one drive
- Exhaust flap without function, slower warm-up
- Further codes for the same fuse or harness
Common causes of P2B98
- Most likelyBlown fuse or interrupted feed to the valve actuator
- PossibleEngine harness chafed and shorted (GM 21-NA-149)
- PossibleCorroded connector or poor ground at the actuator
- Less likelyWeak battery or charging fault causing voltage dips
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 aWiring harness
What each part of P2B98 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| B | Area: hybrid propulsion. |
| 98 | The exact fault in that area. |
What to do next
- Note P2B98 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 P2B98
What does P2B98 mean?
P2B98 means "Exhaust Pressure Control Valve A Supply Low". P2B98 says the motor of exhaust pressure control valve A is not getting enough supply voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P2B98?
Drive gently and only to a workshop. With P2B98 the car can go into limp mode (reduced power) to protect itself.
Will P2B98 fail an emissions test?
Yes, it can. P2B98 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 P2B98 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P2B98 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.