2 Allison diagnostic codes on file — with the full diagnosis, repair steps, and field insights open to read free, no signup required.
Disclaimer: General reference information for trained, qualified technicians only. Codes and procedures vary by model, serial number and software version. Always follow the manufacturer's service manual and your site's safety procedures. Use at your own risk. Not affiliated with or endorsed by any manufacturer.
| Code | System | Symptom | Full fix |
|---|---|---|---|
| P0842 / DTC 42-12 | Pressure Sensing | Check Trans Light / Harsh Downshifts | View fix |
| P0847 | Pressure Sensing | Check Trans / Shift Range Restricted | View fix |
Same codes keep coming back?
That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.
AM Fleet Integrity gives you QR-code operator reporting, preventive maintenance scheduling, and predictive alerts in one place. Start your 14-day free trial — no credit card required.
Start your free trial