Reduced power

Reduced power / limp home mode – is it my exhaust system?

• Modern cars will limit engine speed with ‘limp home’ mode if there is an issue

• Sensors are a likely culprit

‘Limp Home’ Mode

‘Most modern cars will limit engine speed if there is an issue and display an engine warning light, but the car is usually still safe to drive without causing further damage. This is often referred to as ‘limp-home’ mode and it is designed to allow you to get off a busy main road or get to a garage or home if there is a non-critical issue brewing. If you are a member of a roadside recovery service, then pull-over somewhere quiet and call them, if you are within a mile of home, then it may be sensible to head home and call then instead.


Emissions components such as CATs and DPFs and the associated sensors are frequent causes of limp-home mode. It means there is a problem, (usually blockage) with the unit. If it is a blocked DPF then the garage may be able to force regeneration or carry out a DPF cleaning – which may be effective if you have been doing lots of short journeys in a diesel car. If a CAT or a DPF is severely compromised, it will require a full replacement. In addition, entering this driving mode can mean faulty sensors, or a symptom of a bigger engine issue, so this issue does need sorting out.

In all cases, your car needs attention quickly and generally the sooner you stop and call for assistance, the easier it will be to fix. Choosing a highly trained technician and a type-approved part when considering exhaust component replacement can exponentially boost the service life of the new emissions devices or systems. Via this approach, you can minimize damage to the vehicle, while also preserving its original efficiency and performance characteristics.