Main Eco Compact E317 / 162 fault code: wrong electrical frequency

If your Main Eco Compact is showing E317 or 162, Baxi’s current fault-code table describes it as “Wrong power supply electrical frequency (Hz)”. The two numbers are shown together in the official listing as E317 / 162.

This means the boiler has not accepted the frequency of the electrical supply it is seeing. It does not mean the heating temperature is wrong, and it is not the same as a low-voltage code. Keep the boiler closed and do not attempt electrical testing yourself.

What electrical frequency means

UK mains electricity alternates direction in a regular cycle. The number of cycles per second is measured in hertz, abbreviated to Hz. The Main Eco Compact’s current technical specification lists a 230 V, 50 Hz electrical supply.

The boiler’s electronics expect that regular frequency as part of normal operation. If the control system detects a frequency outside what it accepts, the boiler can stop and display E317 / 162 rather than continue on an uncertain supply.

Frequency and voltage are different measurements. Baxi separately lists E385 / 165 as an under-voltage fault. That distinction matters: E317 / 162 should not be relabelled as a voltage problem or treated by guessing at a fuse, control board or household circuit.

Why are there two code numbers?

The official table presents the fault as E317 / 162. Depending on the display, software version or way the fault history is shown, you may see E317, 162 or the paired reference in documentation.

Record exactly what appears on your boiler. Do not add or remove the “E”, and photograph the screen if possible. The paired official listing means both references lead to the same published description: wrong power-supply electrical frequency.

Which boilers can show E317 / 162?

Baxi’s current fault-code table includes Main Eco Compact Combi and Main Eco Compact System in the model group using this code. The same reference appears for several related Baxi and Potterton boilers, but the exact model should still be confirmed before work.

Main Eco Compact Combi models are currently listed in 25 kW and 30 kW outputs, while Main Eco Compact System models are listed in 15 kW and 18 kW outputs. Both current technical specifications state a 230 V, 50 Hz supply.

What you may notice at home

E317 / 162 can stop the boiler from starting or interrupt operation. You may notice:

• the display shows E317, 162 or the related reference;
• the heating does not start when the thermostat calls;
• a combi boiler does not provide hot water;
• the code appeared after a power cut, flicker or restoration;
• the boiler works briefly and then stops again;
• the fault is intermittent rather than permanent;
• other electrical equipment behaved unusually at around the same time.

These observations help establish timing. They do not prove whether the issue is outside the boiler, in the appliance supply or within the boiler’s monitoring. That requires competent electrical and boiler checks.

Safe observations to record

You can collect useful information without opening electrical enclosures or using a test meter:

• Photograph the code and all display symbols.
• Note the exact time and whether the fault followed a power interruption.
• Record whether lights or other appliances flickered at the same time.
• Tell the engineer if the property was using a generator, inverter, battery backup or other alternative supply.
• Note whether the boiler display stayed lit or went completely blank.
• Record whether heating, hot water or both were being requested.
• Write down any other boiler code shown before or after E317 / 162.
• Mention recent professional electrical or boiler work.

If the boiler display is on but the burner will not start, our guide to a boiler not firing up explains other household details worth noting. The exact E317 / 162 code still needs electrical-frequency checks specific to your appliance and supply.

Can you reset Main Eco Compact E317 / 162?

The Main Eco Compact user guide distinguishes between resettable errors and errors that are not resettable by the user. If your display shows the resettable-error symbol and the instructions for your exact model permit it, you can try one normal reset from the front control.

On the referenced Main Eco Compact Combi guide, the reset button is pressed for approximately one second; holding it for more than two seconds will not reset the boiler. Follow your own model guide because controls can vary.

If the code remains or returns, stop resetting. Repeated power cycling will not make an incorrect or unstable supply condition safe, and it can remove useful evidence about when the fault occurs.

What not to do

• Do not remove the boiler casing or electrical covers.
• Do not use a multimeter on the boiler, fused spur or consumer unit.
• Do not change fuses, wiring, earthing or circuit connections to chase the code.
• Do not connect the boiler to a generator, inverter or extension lead as a test.
• Do not alter internal control-board settings or service parameters.
• Do not buy a PCB on the assumption that the display proves it has failed.
• Do not repeatedly switch the boiler or property supply off and on.

Electrical work and internal gas-boiler work require the right competence. A qualified engineer can check the boiler’s stored fault information and establish whether the supply reaching the appliance meets the manufacturer’s requirements. If wider property-supply concerns are found, the appropriate electrical or network professional can then deal with that part safely.

How E317 / 162 differs from E385 / 165

Baxi lists these as separate faults:

• E317 / 162: wrong power-supply electrical frequency in Hz.
• E385 / 165: under voltage.

Frequency describes how often the alternating supply cycles. Voltage describes electrical potential. A homeowner cannot safely distinguish the electrical cause with boiler noises or a visual check, so photograph the exact code rather than describing both as “a power fault”.

When to arrange a repair

Book a repair if E317 / 162 stays on the display, returns after the one permitted reset, or leaves you without reliable heating or hot water. Tell the engineer whether it followed a power cut, whether other equipment was affected and whether any alternative electricity supply was in use.

If there is burning, smoke, scorching, a buzzing electrical enclosure or a smell of overheated wiring, do not touch the boiler or nearby electrical controls. Move away and obtain urgent professional help. If a professional has isolated the appliance, do not turn it back on.

Gas and carbon-monoxide safety

E317 / 162 is an electrical-frequency code, not a gas-leak code. Normal gas safety still applies. If you smell gas, suspect a leak or think the appliance is unsafe, do not reset or operate it. Open doors and windows, turn off gas at the meter if you know how to do so safely, leave the affected area and call the National Gas Emergency Service on 0800 111 999.

If a carbon-monoxide alarm sounds or anyone develops possible symptoms such as headache, dizziness, nausea, breathlessness or unusual tiredness, move into fresh air and seek urgent medical help. Do not use the boiler again until it has been checked and declared safe.

Quick answers about Main Eco Compact E317 / 162

What does E317 / 162 mean?

Baxi lists it as “Wrong power supply electrical frequency (Hz)”. The boiler has not accepted the frequency of the electricity supply it detects.

Is electrical frequency the same as voltage?

No. Frequency is measured in hertz; voltage is a different measurement. Baxi lists under voltage separately as E385 / 165.

Why does the code have two numbers?

The official table pairs E317 with 162 for the same fault description. Photograph exactly what your display shows.

Can I test the supply myself?

No. Do not probe the boiler, fused spur or consumer unit. Electrical testing must be carried out by a competent professional.

Can I reset E317 / 162?

Try one reset only if your exact model’s display and guide mark the error as resettable. If it returns, arrange repair and mention any recent power interruption.