P0171 on Jaguar
System Too Lean (Bank 1)
P0171 on Jaguar vehicles indicates system too lean (bank 1). Au7o has documented this code across 2 Jaguar models — most commonly on XF, XJ. This code means the engine's computer has detected that the air-fuel mixture on Bank 1 (the side of the engine with cylinder #1) is running too lean — meaning there is too much air relative to fuel. The computer watches the oxygen sensors and has had to add a large amount of extra fuel (long-term fuel trim) to try to compensate, but it has hit its correction limit. A lean condition can cause rough idle, hesitation, reduced power, and over time can run the engine hotter than normal. It usually points to either unmetered air leaking into the engine or not enough fuel being delivered. Typical repair costs on Jaguar range from $400 to $1,500, depending on the specific model and root cause.
Common Causes of P0171
- •Vacuum or intake air leak (cracked hose, gasket, or PCV system)
- •Dirty or failing mass airflow (MAF) sensor
- •Weak fuel pump or restricted fuel filter
- •Clogged or dirty fuel injectors
- •Faulty or aged upstream oxygen sensor
- •Leaking intake manifold gasket
- •Low fuel pressure or failing fuel pressure regulator
- •Exhaust leak ahead of the oxygen sensor
P0171 on Jaguar by Model
Jaguar XF(1 issue)
- Crankcase Ventilation Valve Failure on AJ-V82009-2015
The crankcase ventilation (PCV) valve on AJ-V8 engines fails, causing excessive oil consumption, oil leaks from gaskets under positive crankcase pressure, and rough idle. The valve diaphragm tears, disrupting crankcase pressure management.
Jaguar XJ(1 issue)
- X350 Saddle-Tank Twin Fuel Pump / Jet Pump Failure — Stalling, Hesitation and Erratic Fuel Gauge2004-2009
The 2004-2009 X350/X358 uses a saddle-shaped fuel tank straddling the driveshaft, with a lift pump on one side and a venturi jet pump transferring fuel from the other. When the jet pump or the lift pump module degrades, the engine side of the tank runs dry even though the gauge shows fuel: owners report momentary stutters or stalls at highway speed, hard starts in cold weather, and gauges that drop suddenly or read unreliably because the level senders are built into the non-serviceable pump modules. It affects the V8 and V6 petrol cars and the 2.7 diesel. The pump module is a sealed unit so the sender is replaced with the pump.
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View P0171 across all makes →Frequently Asked Questions
What does P0171 mean on Jaguar?▼
P0171 stands for "System Too Lean (Bank 1)." This code means the engine's computer has detected that the air-fuel mixture on Bank 1 (the side of the engine with cylinder #1) is running too lean — meaning there is too much air relative to fuel. The computer watches the oxygen sensors and has had to add a large amount of extra fuel (long-term fuel trim) to try to compensate, but it has hit its correction limit. A lean condition can cause rough idle, hesitation, reduced power, and over time can run the engine hotter than normal. It usually points to either unmetered air leaking into the engine or not enough fuel being delivered. On Jaguar specifically, this code is documented across 2 models.
What causes P0171 on Jaguar vehicles?▼
Common causes on Jaguar: Vacuum or intake air leak (cracked hose, gasket, or PCV system), Dirty or failing mass airflow (MAF) sensor, Weak fuel pump or restricted fuel filter, Clogged or dirty fuel injectors, Faulty or aged upstream oxygen sensor. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0171 on a Jaguar?▼
Repair costs on Jaguar range from $400 to $1,500, depending on the specific model and root cause.
Which Jaguar models have P0171 documented?▼
Au7o has documented P0171 on 2 Jaguar models: XF, XJ.