Land Rover Discovery II P0171, P0174, P1172, P1175, P0734 Codes: Diagnosis and Fixes
My Land Rover Discovery II is displaying multiple OBD-II diagnostic codes: P0171, P0174, P1172, P1175, and P0736. I've researched the meanings of these codes but am missing specific causes and troubleshooting steps—especially for P0734. Code P0734: Fourth Gear Incorrect Ratio — This indicates a mismatch in gear ratio within the transmission. A potential cause could be transmission slipping, especially if the vehicle has an automatic transmission. Suspension modifications or transfer case issues may also play a role. Codes P0171 and P0174 are generic 'fuel trim' codes indicating the engine is running lean (too much air, not enough fuel). Common causes include vacuum leaks, low fuel pressure, clogged fuel injectors, or faulty oxygen sensors. These issues typically affect the entire engine system. Codes P1172 and P1175 are Land Rover-specific and require vehicle model-year and engine type details for accurate diagnosis. These codes often relate to fuel trim or camshaft position sensor malfunctions. As Land Rover vehicles use proprietary components, they are generally serviced by authorized dealerships due to specialized tools and parts. I'm seeking advice on how to identify the root cause of these issues—especially P1172 and P1175—and whether a DIY repair is feasible or if professional diagnosis at a dealership is recommended.
Please provide your Land Rover Discovery II's engine type, transmission (automatic or manual), and model year. This information is critical for accurate troubleshooting. P0734: Fourth Gear Incorrect Ratio — This code typically points to a transmission issue such as gear ratio mismatch or slipping. If the vehicle has an automatic transmission, internal wear or fluid degradation could be factors. Suspension modifications or transfer case problems may also contribute. P0171 and P0174 are generic codes indicating lean engine conditions. Common causes include vacuum leaks, low fuel pressure, clogged fuel injectors, or faulty oxygen sensors. These issues often require a full system check using diagnostic tools. For P1172 and P1175 (Land Rover-specific), these codes may relate to fuel trim malfunctions or camshaft position sensor faults. Since Land Rover vehicles use proprietary systems and components, detailed technical documentation is not widely available outside official service manuals. These issues are best diagnosed with specialized equipment found only at authorized dealerships. While some DIY fixes might apply to P0171/P0174, the P1172 and P1175 codes require expert-level knowledge and tools—making a dealership visit highly recommended.