Will installing a new DEF heater resolve this issue or is there other steps I should look into first?
Nov 7, 2019 at 7:28 PM
Code P20b9 and “service exhaust system” warning on
2015 GMC SIERRA
CHARLIE1229
- MEMBER
- 46 POSTS
- FOLLOW
Repair Safety Notice:
This information is for general instructional purposes only. Vehicle repair can be dangerous.
Verify all information, follow manufacturer service procedures, use proper tools and safety equipment,
and consult a qualified repair shop when needed.
Advertisement
Hi:
I believe that code is related to the DEF system running it's own self test and not the heater. Try this. An onboard test must be commanded using a scan tool. A fluid quality test or a forced REGEN will make the monitor run and the messages should clear and the system should return to normal. Basically, you need to force a fluid quality test using a scan tool.
Try this and let me know if it helps.
Joe
I believe that code is related to the DEF system running it's own self test and not the heater. Try this. An onboard test must be commanded using a scan tool. A fluid quality test or a forced REGEN will make the monitor run and the messages should clear and the system should return to normal. Basically, you need to force a fluid quality test using a scan tool.
Try this and let me know if it helps.
Joe
Nov 8, 2019 at 6:15 PM
Advertisement