AI Damage2021 MCI D4520: common problems
The maker issued 11 service bulletins for this year. Details by component below, with sources.
Key figures
- Technical service bulletins (TSB)
- 11
Components owners complain about
| Component | Owner complaints | involving a crash | Technical service bulletins (TSB) |
|---|---|---|---|
| Structure | 0 | 0 | 3 |
| Electrical system | 0 | 0 | 2 |
| Engine | 0 | 0 | 2 |
| Fuel system | 0 | 0 | 2 |
| Service brakes | 0 | 0 | 2 |
| Engine and cooling | 0 | 0 | 1 |
| Latches, locks, linkages | 0 | 0 | 1 |
| Steering | 0 | 0 | 1 |
| Suspension | 0 | 0 | 1 |
| Other | 0 | 0 | 1 |
Comparison
What to check before buying
- Structure. Rails, pillars, panel gaps, signs of pulling or welding.
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
- Engine. Cold start, unusual noises, oil leaks and engine codes.
- Fuel system. Fuel smell, leaks, rough running, fuel-system codes.
Manufacturer service bulletins
Bulletin titles as filed with NHTSA.
- This bulletin is to provide instructions for clearing DTC 1067 FMI 7 (Pressure Sensor Not Calibrated) and…
This bulletin is to provide instructions for clearing DTC 1067 FMI 7 (Pressure Sensor Not Calibrated) and FMI 11 (Primary and Secondary Circuit Pressure Sensor (PS1/PS2) Plausibility Error - BS Pressure), when required…
- This bulletin introduces an optional product improvement to the A/C compressor drive system for coaches…
This bulletin introduces an optional product improvement to the A/C compressor drive system for coaches equipped with a Cummins X12. The improved pulley system is available for customers who wish to reduce noise and…
- This TSIB provides information to provide a software update
Some coaches using MCC HVAC Eco-Tempo ECU # 07-10-009 software T35-1581 / V1.04 may be experiencing random fault codes due to MCC software errors.
- This TSIB is to inform customers the recommended steering axle cleaning/greasing instructions to prevent…
This TSIB is to inform customers the recommended steering axle cleaning/greasing instructions to prevent damage on axle components due to displacement of grease from the bearings, lubrication reduction and accelerate…
- Information to owners showing the proper procedure for checking the oil level in a BITZER HVAC compressor
- Service instruction for updating plug doors to improve reliability and reduce wind noise
- Instructions to properly adjust entrance door to ensure proper operation
- Instructions for improving fuel tank venting while fueling
- Technical Service Information Bulletin describing the retrofit for the front junction box cover on…
Technical Service Information Bulletin describing the retrofit for the front junction box cover on specifically equipped buses.
- This Technical Service Information Bulletin is a supplemental reminder to all MCI owners/operators of…
This Technical Service Information Bulletin is a supplemental reminder to all MCI owners/operators of vehicles which are affected by the Cummins Equipment Recall 21E-099 and MCI Vehicle recall 21V-971.
- This Technical Service Information Bulletin (TSIB) describes an update from Meritor for the bolt torque…
This Technical Service Information Bulletin (TSIB) describes an update from Meritor for the bolt torque application requirements on hub-to-rotor bolts for the front, drive and tag axles, on specific coaches equipped…
Other years of this model
Questions and answers
What are the most common problems with the 2021 MCI D4520?
There are no owner complaints in the NHTSA data for this year; the data comes from 11 manufacturer service bulletins.
How many service bulletins (TSB) were issued for the 2021 MCI D4520?
NHTSA lists 11 manufacturer service bulletins for this year. A bulletin tells dealers how to diagnose or fix a known issue; it is not a recall.
Should I buy a 2021 MCI D4520 from a US auction?
Owner complaints describe defects, not crash damage. Before bidding, check the components listed above and review the lot photos: VinWind builds a report of visible and hidden damage by VIN.
Other 2021 models
Read also
Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-04.