O2 Oxygen Sensor Upstream Downstream for Jaguar XJR (2004-2005) 4.2L Supercharged

Direct-Fit O2 Sensor Kit for 2004-2005 Jaguar XJR (X350)

What it Does: This 4-piece upstream and downstream oxygen sensor kit monitors exhaust air-fuel ratios on the 2004-2005 Jaguar XJR (X350) AJ34S 4.2L Supercharged V8 to maintain closed-loop fueling and emissions compliance.

The Stock Jaguar XJR Sensor Failure

Sustained boost from the factory supercharger subjects the X350 chassis and AJ34S 4.2L Supercharged V8 to extreme exhaust temperatures that degrade OEM zirconia sensing elements. Carbon fouling, thermal shock, and internal heater circuit burnout slow voltage switching over time. Aged sensors matching 234-9030 and 234-4798 skew closed-loop fuel trims, triggering P0130, P0135, and P0171/P0174 codes while masking true catalytic converter efficiency.

Common Symptoms of a Failing OEM Oxygen Sensor

• Check Engine Light / DTCs: Triggers heater and slow-response codes like P0135, P0155, or P0420/P0430.
• Fuel Trim Drift: Erratic voltage forces rich open-loop fueling under supercharged boost.
• Failed Emissions: Delayed closed-loop control increases exhaust pollutants and cuts fuel economy.

The Direct-Fit 4-Piece Oxygen Sensor Solution

Replacing all four sensors simultaneously restores balanced bank-to-bank air-fuel feedback across both cylinder banks of the AJ34S 4.2L Supercharged V8. Each direct-fit sensor utilizes a fast-light-off internal heater, double-layered stainless protective shield, and zirconia ceramic element built for high-heat forced-induction exhaust on the X350. Factory-length leads and OEM-style weatherproof connectors directly replace 234-9030 upstream and 234-4798 downstream units with zero splicing.

What's Included

• 2x Upstream Oxygen Sensors
• 2x Downstream Oxygen Sensors

Technical Specifications

Compatibility

• 2004-2005 Jaguar XJR 4.2L Supercharged (4-Piece Set)

Frequently Asked Questions & Fitment Warnings

Does this fit the X350 XJR?

Yes. Fits 2004-2005 Jaguar XJR models with the AJ34S 4.2L Supercharged V8. XJ8 4.2L non-supercharged models require a separate listing; confirm engine before ordering.

Will this clear P0130, P0135, or P0171/P0174 codes?

Yes, if sensors are faulty. New 234-9030 and 234-4798 units restore heater resistance and signal speed after clearing DTCs.

Are connectors plug-and-play?

Yes. Pre-wired OEM-style connectors thread directly into factory bungs with no cutting or splicing required.

The Jaguar Precision Standard

Built for European emissions accuracy and ECU precision, this 4-sensor kit keeps your X350 running clean and CEL-free. Maintain factory closed-loop fuel control.