Rheem Error Code A091: PCB Communication Error
Warning: Your Rheem HVAC system has a PCB communication error, which may cause system malfunctions. It's safe to troubleshoot, but call a professional if needed.
How to Fix Rheem Code A091
- Check and tighten all electrical connections
- Inspect wiring and connectors for damage or corrosion
- Try resetting the system by turning off the power at the breaker for 30 seconds and then turning it back on
How to Reset Rheem Code A091
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Rheem Error Code A091 Mean?
The Rheem A091 error code indicates a communication issue between the main PCB (Printed Circuit Board) and other system components. This could be due to a faulty wire, connector, or the PCB itself. The system may not operate correctly or might display other error codes as a result.
Common Causes
- Faulty or damaged wiring or connectors
- Defective main PCB
- Loose or corroded electrical connections
- Intermittent power supply issues
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| System displays other error codes along with A091 | Check for any visible damage or disconnection in the wiring harness | No visible damage or disconnection |
| Power supply to the main PCB is intermittent | Measure the voltage at the PCB's power input terminals | Stable 24V AC power |
Applicable Rheem Models
- NCB(gas)
- NPE(electric)
- R801T(gas)
- R92E(electric)
- R92V(gas)
- RGE(gas)
- RH2T(electric)
- RNC(dual_fuel)
- RNE(electric)
- RNG(gas)
- RP16(electric)
- RPB(gas)
- RTGH(gas)
- Rheem Classic(gas)
- Rheem Classic 80 Plus(gas)
- Rheem Classic 80% Gas Furnace(gas)
- Rheem Classic 90 Plus(gas)
- Rheem Classic Plus Series(gas)
- Rheem Classic Series(dual_fuel)
- Rheem Prestige(gas)
- Rheem Prestige 95% Gas Furnace(gas)
- Rheem Prestige Series(gas)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Main PCB | RHEEM-301435 | — | Find Part |
| Wiring harness | — | — | — |
Related Codes on Same Models
Other codes that affect the same Rheem model families as A091.
| Code | Description | Severity |
|---|---|---|
| A001 | Ignition Failure | Warning |
| A021 | Over-Temperature | Warning |
| A031 | Inlet Thermistor Open/Short | Warning |
| A041 | Outlet Thermistor Open/Short | Warning |
| A043 | Water Level Error | Warning |
| A051 | Fan Motor Abnormality | Warning |
| A052 | Fan Motor Speed Error | Warning |
| A053 | Fan Motor Open Circuit | Warning |
| A054 | Fan Motor Overcurrent | Warning |
| A055 | Fan Motor Locked | Warning |