ERR4278 | Throttle Potentiometer - V8 EFI | Defender, Discovery 1, Range Rover P38
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To check the stock of Genuine Parts before placing an order please use our Contact Us page
Land Rover Part Number: ERR4278 - Throttle Potentiometer
ERR4278 is a throttle potentiometer used on Rover V8 EFI engines. Fitted to the throttle body or plenum chamber, the sensor provides a variable resistance (voltage) signal proportional to the throttle-plate angle so the engine management unit can adjust fuel delivery, ignition timing and idle control. The sensor is suitable for 4.0 and 4.6 litre Rover V8 EFI applications fitted to the models listed below. Replacement is recommended when the sensor produces erratic signals, causes poor throttle response or triggers engine-management fault codes that indicate throttle position feedback; use the compatibility data below to confirm fitment against your V.I.N.
Compatibility
- Defender (1987-2006) - 4.0 V8 EFI
- Discovery 1 (1989-1998) - 3.9/4.0 V8 EFI (From FA393361 to WA799999)
- Range Rover P38 (1994-2001) - 4.0 V8 EFI, 4.6 V8 EFI
Frequently Asked Questions
ERR4278 is the throttle position sensor (potentiometer) on Rover V8 multi-point EFI systems. It supplies a variable resistance/voltage signal proportional to throttle-plate angle to the engine management unit so fuel delivery, ignition timing and idle control can be adjusted. Faulty units commonly produce erratic signals, poor throttle response or engine-management fault codes that reference throttle position feedback, and should be replaced when these symptoms occur.
| Model | Variant |
|---|---|
| Land Rover Defender | 1987 - 2006 - 4.0 V8 EFI |
| Land Rover Discovery 1 | 1989 - 1998 - 3.9/4.0 V8 EFI (From FA393361 to WA799999) |
| Land Rover Range Rover P38 | 1994 - 2001 - 4.0 V8 EFI |
| Land Rover Range Rover P38 | 1994 - 2001 - 4.6 V8 EFI (including various market / LHD variants) |
If you are unsure of compatibility with your vehicle, you can also confirm by checking against your V.I.N. Simply reach out to us with your V.I.N and desired part number via our Contact page or use our Finding Part Numbers page.
Replace ERR4278 if it produces erratic voltage signals, causes poor throttle response or triggers throttle position-related engine fault codes. If unsure, confirm fitment by V.I.N. and have the vehicle diagnosed by a qualified technician.
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