BoilerFaultCodesWhat the manual says
Manufacturer manualReturn sensor defective (zone 1)
Shared across the range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
What causes this fault?
This fault occurs when the internal computer can no longer read a consistent or accurate signal from the sensor that monitors water returning from your radiators. The most common reason is that the sensor's internal electrical resistance has failed, but it can also be caused by loose or corroded wiring connections inside the boiler.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Related fault codes
All 93 fault codes on the Microsystem 15
Seeing a different code? Every code this model can display, in one place.
1 011 031 041 051 061 071 091 101 121 141 161 181 P11 P21 P31 P42 053 013 023 033 043 053 063 073 P94 114 124 135 015 025 045 P15 P25 P36 106 127 017 027 037 127 137 227 237 5010121314108591A01A02A03A04A05A06A07A08A09A10A11A12A33AA0011AA0022AA0033AA0077AA3333AA9999B01B02B03B05B06B07B08BOILER SHUTDOWNE08E33E95EE 0044EE 0055EE 0088EE 2200EE 9999Ignition LockoutINSUFFICIENT WATERInsufficient water pressureL.E.D. DL.E.D. GLimescale Build-upSafety Shut-off