Faulty control board
The A070 error code on Rheem boilers indicates faulty control board.
Rheem A070 means: faulty control board. The usual causes are faulty or worn ignition electrode, cracked or dirty ignition lead or gas supply interruption or low gas pressure. You can safely reset the boiler once — if A070 returns, do not keep resetting. A qualified heating engineer should diagnose the root cause.
What Does A070 Mean
The A070 code is shown by the boiler’s control board when it detects faulty control board. The boiler then stops instead of continuing to run in that condition: the code is the appliance reporting a problem, not proof that the boiler is broken.
| What you see on the boiler |
|---|
| The display shows A070 and the boiler stops until the fault is cleared |
Common Causes
Causes documented in 2 technical sources.
| Cause |
|---|
| Faulty or worn ignition electrode |
| cracked or dirty ignition lead |
| gas supply interruption or low gas pressure |
| blocked condensate drain preventing ignition |
| defective gas valve not opening |
| faulty PCB (printed circuit board) not sending ignition signal |
Safety Warning
A070 involves electrical or pressure-related components. Do not attempt repairs without proper qualifications. Ensure the boiler is electrically isolated before any inspection. If you notice water leaks, unusual sounds, or pressure anomalies, contact a qualified heating engineer immediately.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
Step-by-Step Diagnosis
Check for visible damage on the PCB — look for burnt components, corrosion, or water marks
Check all wiring connections to the PCB are secure
Try a power cycle — switch the boiler off at the mains for 30 seconds, then switch back on
If the fault persists after power cycling, check the error code history for related faults
Verify the mains voltage supply to the PCB is stable (230V ±10%)
Check the earth connection
How to Fix It
Clean or replace the ignition electrode and lead
clear any condensate blockage (pour warm water over frozen external pipe in winter)
reset the boiler after checking all components
if the gas valve is not opening, replace the gas valve (Gas Safe registered engineer required)
if the PCB is not sending ignition signal, replace the PCB. Important: all gas work must be carried out by a Gas Safe registered engineer
Refer to the Rheem service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
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Affected Models
Rheem models that can display fault code A070:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Rheem models | — | Possible |
Frequently Asked Questions
Clean or replace the ignition electrode and lead. According to the technical documentation, this is the first check on the list for A070.
A070 is not classified as a high-severity fault, so the boiler can be reset once. If A070 comes back, stop resetting: the underlying cause is still there and needs a qualified heating engineer.