Overview
E.02 – .20 on a Baxi 200/400 Combi indicates a permanent configuration fault: the boiler control PCB has detected that "jumper 2" is in the wrong position (the board's fitted configuration does not match expected settings). Jumpers are small link connectors on the PCB used to set model/configuration options after manufacture or repair. When the board sees an unexpected jumper state it will register a permanent fault and usually lock out the boiler to prevent unsafe or incorrect operation. Severity is medium to high because the boiler will likely be locked out or refuse to operate until the configuration is corrected. This is not a simple sensor or pressure issue and changing jumpers affects how the control board communicates with valves and safety systems. For most homeowners this is not a DIY job unless you have the boiler wiring diagram, the service manual, and experience working safely inside boilers. If you are unsure, or if you find signs of damage, corrosion or repeated faults, contact a Gas Safe registered engineer to diagnose and correct the configuration and test the boiler.
Possible Cause: Jumper 2 changed – check position of jumper 2.
Troubleshooting Steps
Safety precautions:
Turn off the boiler at the electrical isolator and switch off the gas supply if you suspect any gas smell. If you smell gas, do not touch the boiler; ventilate the area and call the gas emergency number immediately. Only work with the front cover removed if you are competent and confident working on electrical equipment and gas appliances; internal PCB work should only be done by a trained person. Use insulated tools, keep the area dry, and avoid metal jewelry. Always resecure covers before restoring power.
Initial checks a homeowner can do (no internal access required):
1. Try a simple reset first: follow the boiler’s reset procedure (press and hold the reset/selector as per manual for 3–10 seconds). A reset can clear transient faults but will not permanently correct a mis-set jumper. Do not attempt multiple resets repeatedly if the code returns.
2. Check basic operational items: confirm boiler has power, the system pressure is reasonable (typically 1–1.5 bar for a cold system), and the gas supply is on. Low pressure or no gas can cause other error codes but are not the root cause for a jumper change fault.
3. Note any other fault codes displayed alongside E.02 – .20 and report them to a servicing engineer; multiple codes can indicate a related fault or a failing PCB.
Specific diagnostic and (qualified) fix steps for a competent person or engineer:
1. Consult the service manual or wiring diagram for your exact Baxi 200/400 combi model to confirm the correct position for jumper 2. The correct jumper positions are model and configuration dependent and should be verified from official documentation or the PCB silk-screening.
2. Isolate electrical supply at the mains and, if working around gas components, isolate gas supply. Wait a short time for capacitors to discharge.
3. Remove the boiler front cover following the manufacturer’s instructions. Locate the main PCB and the jumper block. The jumpers are small removable shunts or soldered links usually labelled on the board.
4. Visually inspect the PCB for damage, loose connectors, corrosion, or signs of previous tampering. A jumper in the wrong position can be caused by a replacement board or by someone moving jumpers without following procedure.
5. If you have verified the correct position and are competent to do so, move jumper 2 to the correct position using appropriate tools. If the jumper is soldered or the board looks damaged, do not attempt to desolder or repair – call a professional.
6. Refit the cover, restore mains and gas, and perform a controlled reset of the boiler. Observe the display: if the E.02 – .20 code clears and the boiler starts normally, run the heating and hot water cycles to confirm stable operation.
7. If the code returns, or if other faults appear, do not continue to reset repeatedly. Persistent reappearance can indicate a faulty PCB, intermittent connector, or incorrect board fitted; these require a Gas Safe registered engineer and possibly replacement of parts.
When to call a professional:
If you are not experienced with internal boiler electronics and gas appliances, do not open the boiler or alter jumpers yourself. Any configuration or PCB work should be completed and tested by a Gas Safe registered engineer. Call a Gas Safe engineer if the fault persists after a reset, if jumper 2 cannot be returned to the correct position, if the PCB shows physical damage, or if you see multiple related fault codes. The engineer will confirm the correct configuration, carry out safe repairs or PCB replacement, and perform combustion and safety checks before returning the boiler to service.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Baxi 200 / 400 Combi Gas Boiler.