Worcester Bosch Boiler E2 Error Code

Heating flow temperature sensor fault on Worcester Bosch boilers.

Worcester Bosch All Worcester Bosch boiler codes

May need a pro

The boiler can't get a believable reading from the NTC thermistor on the heating flow pipe. Worcester's booklet lists a corroded plug, a broken lead, a failed sensor or the PCB. The boiler is blocked from running until it's sorted.

Compatible models

Covered in the user instructions for Greenstar CDi Classic ErP combis and HighFlow 440CDi and 550CDi ErP, and in the engineer's booklet for CDi Classic boilers.

Also shown as

No other codes are listed for this fault.

Difficulty

Try the basic checks, but the usual fix is a technician's job.

How to fix
When to call a pro
Parts
FAQ

Not sure you are reading the code right? See how to read Worcester Bosch boiler codes.

Safety first: never take the casing off a gas boiler. If you smell gas, open windows, don't use light switches, turn the gas off at the meter if you can and call your gas emergency number from outside. A carbon monoxide alarm going off means the same: switch the boiler off, get fresh air and call.

How to fix Worcester Bosch E2

Try a single restart
Switch off at the fused spur, wait a minute, switch on. If E2 shows again, there's nothing else for you to try from outside the casing.

When to call a technician

Replacing the sensor or its lead is a Gas Safe engineer job.

Parts linked to E2

These are the parts an engineer usually checks for this code. They sit inside the sealed casing, so leave them to a Gas Safe registered engineer.

Frequently asked questions

Which Worcester Bosch models show the E2 code?

Covered in the user instructions for Greenstar CDi Classic ErP combis and HighFlow 440CDi and 550CDi ErP, and in the engineer's booklet for CDi Classic boilers.

Can I fix Worcester Bosch E2 myself?

Only the outside checks above. If they don't clear E2, the fix is inside the boiler and needs a Gas Safe registered engineer.

Other Worcester Bosch boiler codes

Last reviewed 2026-10-21. Codes and steps can vary by model; check your owner's manual.

Sources we checked