Discovery Sport Adaptive Cruise Control & Stop/Start Issues: A Frustrated Owner’s Deep Dive

Many Discovery Sport owners appreciate the vehicle’s advanced features, including the Adaptive Cruise Control with Stop & Go functionality. However, some, like this owner, have faced persistent and perplexing issues with these systems. This detailed account explores the frustrating experience of a Discovery Sport owner battling recurring problems with the stop/start system and uncovering anomalies with the adaptive cruise control. After seven attempts to fix the stop/start and meticulous data logging over 15,000 kilometers, a clear pattern of malfunction remains elusive, leading to deeper concerns about the vehicle’s computer system and overall reliability.

Persistent Stop/Start System Failures: A Seven-Time Saga

The owner’s journey with their Discovery Sport’s stop/start system has been anything but smooth, marked by an astonishing seven repair attempts. Unlike some reported cases linked to gateway module issues, this vehicle apparently has a healthy charging system and battery. Despite this, the stop/start malfunction persists. Driven by frustration and a desire for answers, the owner embarked on an extensive data logging exercise, meticulously tracking every parameter that should influence the stop/start system’s operation.

For over 15,000 kilometers, every trip was documented. This included:

• Features enabled and disabled.
• Ambient temperature at the start and end of each journey.
• Instances of stop/start activation (successful, partial, or complete failure).
• Engine temperature relative to the “blue” notch indicator at stops.
• Daily battery voltage measurements (morning and evening).

Even after isolating variables by deactivating all ancillary features for a 4,000km data subset, no predictable behavior emerged. The system’s operation remained erratic, defying logical explanation based on handbook parameters or common troubleshooting. There were even instances of delayed activation, with the stop/start engaging after a minute or more of idling at a standstill.

Alt text: Discovery Sport dashboard displaying Adaptive Cruise Control active, illustrating system settings and driver interface.

Fuel Efficiency Discrepancies Raise Further Questions

Adding to the owner’s woes are significant discrepancies in fuel efficiency. The car’s computer reports an average consumption of 10L/100km in city driving conditions – scenarios involving frequent stops and moderate average speeds. However, real-world refueling data contradicts this. Despite driving the same routes, at similar times, and with comparable driving styles as the previous year, the actual fuel consumption remains consistent with a period when the computer displayed a more economical 8.2 – 8.5L/100km for identical journeys. This anomaly suggests the computer’s fuel efficiency calculations are unreliable, further fueling suspicions about broader electronic system issues.

Adaptive Cruise Control Lapses on Downhill Slopes

The problems extend beyond the stop/start and fuel consumption, manifesting in the Adaptive Cruise Control’s performance. While the system effectively maintains set speeds on flat roads and inclines, it falters on even slight downhill gradients. Instead of smoothly adjusting, the system noticeably applies the brakes intermittently before seemingly disengaging speed control altogether. This results in unintended acceleration downhill, quickly exceeding the set speed and potentially leading to unsafe situations. The driver reports feeling the brakes engage and then release, indicating a malfunction in the system’s ability to manage speed proactively on declines.

Alt text: Warning light on Discovery Sport dashboard indicating a Stop/Start system fault, highlighting a common issue for some owners.

Computer System Suspicions and Dealer Confrontation

Based on the accumulated data and consistent malfunctions across different systems, the owner suspects a fundamental issue with the car’s computer. They hypothesize that the stop/start problem isn’t battery-related, but rather stems from incorrect signals or misinterpretations within the drive-by-wire system, potentially orchestrated by a faulty central computer. The fuel efficiency inaccuracies and cruise control inconsistencies further reinforce this theory.

Armed with 15,000km of logged data, the owner is scheduled to meet with the General Manager of their JLR dealership. They intend to present their findings and demand a comprehensive resolution, even if it necessitates replacing major components, including the car’s computer and a system re-flash. The owner’s patience is understandably exhausted, and they are prepared to return the vehicle permanently until all issues are definitively resolved, highlighting a deeply unsatisfactory ownership experience.

This Discovery Sport owner’s detailed account serves as a stark reminder of the complexities of modern automotive systems and the frustrations that can arise when advanced features like Adaptive Cruise Control with Stop & Go activation malfunction persistently. It underscores the importance of thorough diagnostics and effective solutions from dealerships to maintain customer trust and satisfaction in the Land Rover brand.