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Malfunction Indicator Lamp

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Benny_Cornwall
Posts: 46
Joined: Mon Feb 02, 2026 9:05 pm

This is somewhat peculiar; while I was driving back from Stansted on the M5, the check engine light illuminated, yet there was no power loss and the vehicle was operating normally at an average of 47 mpg.
Employed an OBD scanner that indicated a fault code for inadequate EGR flow detected.
Upon returning home, I scheduled an appointment with JLR for an examination later this week; however, I just refuelled and the warning light has extinguished. I opted for premium diesel as I had heard that inferior fuel can lead to complications.
Any insights or recommendations would be valued.
ChristousPapous
Posts: 84
Joined: Mon Feb 02, 2026 9:00 pm

The inexpensive supermarket fuel, upon its introduction, is essentially diluted, resulting in incomplete combustion and subsequent carbon accumulation, which typically leads to an EGR malfunction—the minuscule butterfly valve becomes stuck—thereby causing the EGR sensor to detect insufficient flow through the EGR. If the EGR becomes carbonised, it results in a more polluted combustion process, triggering a chain reaction. This may incur significant expenses to amend if it escalates excessively. Given the elevated cost of premium fuel, it might be more economical to supplement the inexpensive fuel with Redex each time you refuel. Do you frequently undertake brief trips? If that is the case, I would endeavour to locate a lengthier trip weekly for a period, specifically one where you can maintain speeds exceeding 70mph for at least 15 minutes and assess the outcome. Alternative solutions will incur a minimum expense of £500 and may necessitate the combination of three options to fully rectify the issue.
Benny_Cornwall
Posts: 46
Joined: Mon Feb 02, 2026 9:05 pm

I appreciate the information provided overall. I primarily undertake extensive journeys that combine both professional and personal purposes, accumulating approximately 15,000 motorway miles annually; I suspect the problem originated from the fuel I purchased at Stanstead, as the check light extinguished after refuelling at my local Texaco in Cornwall.
Noble4u
Posts: 84
Joined: Mon Feb 02, 2026 8:48 pm

I consistently utilise high-octane fuel and have experienced the warning light illuminating only once in over a decade of ownership.
Indeed, premium petrol is quite costly currently; however, keep in mind that you possess a luxury vehicle.
Labusthetormentor
Posts: 62
Joined: Mon Feb 02, 2026 9:03 pm

Just one of those occurrences, then.
Noble4u
Posts: 84
Joined: Mon Feb 02, 2026 8:48 pm

Ideally resolved then👍👍🤞🤞👍👍
Benny_Cornwall
Posts: 46
Joined: Mon Feb 02, 2026 9:05 pm

Affirmative 🤞
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