The worst 1991 Mack R problems
Ranked by number of owner complaints. Mileage and cost come from what owners wrote.
Problems by type
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Recalls 1
Vehicle speed control
- What is wrong
- Fuel injection system reconfiguration to comply with engine emission standards cause higher engine vibration levels which lead to early wear and complete failure of the secondary throttle return mechanism.
- Risk
- In the event the primary throttle return fails, failure of the secondary throttle return system would not provide protection against loss of throttle control.
- Remedy
- A new production secondary throttle return system configuration will be installed.
Recall number 94V032000 · Recall details
Technical service bulletins for the 1991 Mack R 22
Bulletins tell dealers how to fix known problems. A warranty extension means the manufacturer pays for that repair for longer.
- US10 Emission Engines
- Automated Manual Transmission ( AMT ) I-Shift / mDRIVE
- (Back Office)
- Programming Failure
- NOx Sensor Troubleshooting Guide
- Use for new vehicles (US21+OBD22
- Selective Catalytic Reduction (SCR) Muffler Troubleshooting Guide
- DEF Pump Troubleshooting Guide
- Temperature Sensor Troubleshooting Guide
- Mack Chassis
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Questions about the 1991 Mack R
Is the 1991 Mack R reliable?
Owners have filed 0 complaints about the 1991 Mack R.
What is the most common problem with the 1991 Mack R?
There are not enough complaints to tell.
How many recalls does the 1991 Mack R have?
1 recall, covering vehicle speed control.
VIN decoder
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