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403 Petrol Tank Sender Unit

Can anyone tell me what the resistance range should be for the tank sender unit.  My car has at some time in its past had an after-market unit fitted which does not seem to properly drive the petrol gauge.  It has a resistance range of empty 15Ω (where the gauge shows empty) and full a resistance of 129Ω where the gauge shows just slightly above empty, so something is not right.

Any help gratefully received.

Andrew Sait

My 403 fuel gauge sender looks original. I measured it this evening at 10Ohms to 80 Ohms. I have not run the car since I bought it five years ago (its in bits undergoing a major DIY restoration) but I do know that it had some fuel in the tank and was reading something sensible at the dashboard when I drove it into the garage all that time ago. I also temporarily connected the sender unit to the gauge and manually moved the float over its range and the gauge responded as expected. Hope that helps.

Mike 403-1402


I have now seen your reply.  On Andy Gibbs advice I purchased a sender unit listed as for the Jaguar XK150.  I tested it before I fitted it and the resistance range is exactly as you have outlined above.

Many thanks for your reply.

Kind regards,

Andrew Sait