Hello all,

I think this question is going to Disco Mike. I need to know what code "21" is referring to on a 95 Disco 3.9L ON board fault display? The article I found is referring to a "open fuel resistor or damage to the wire harness" related to the code. I have search the Rave cd and I didn't get any hits for "Fuel Tune resistor". Currently, my rover's gas mileage has gone to crap. I don't have a rough idle and I made sure the MAF sensor is working correctly. Also, the truck has a new set of cats w/ new o2 sensors. Where would this resistor(s)/harness be located if it is "open"? Have comments/insight would be great. Thanks!!

 

That sounds like a O2 Sensor fault. Esp since in general the O2 sensor, front O2 sensor is the one which controls the fuel tuning. This is a general automotive observation tho. You know know what those Limey's are up to with their codes!

 

John, send me your number and I'll call you.

 

What part of the world are you in?

the "tune resistor" is a simple .5 watt, 3900 ohm resistor (NAS) added to the ECU between pin 5 (power) and 27(ground) in the ecu harness as a way of meeting emissions requirements in various regions throughout the world while only having to manufature and install one ECU. To test, just place the ohmeter probes between those two pins on the back of the ecu and check for resistance. BUT FIRST!... disconnect the plug from the ecu and disconnect the battery.

Check the VIN of your rig to make sure it was made before Vin #LA451517. If it is after that number then you do not have a tune resistor.

I am betting the O2 sensors you have in there are not correct for your model. The correct O2 for your year is this one... ONLY... NTK 25016 -- http://www.amazon.com/s/ref=nb_sb_no...ords=ntk+25016

 

You may want to edit that last post of yours to remove the phone number and send it to Mike in a private message. The WWW is a strange place.

remember to check your vin number to see if you even have a tune resistor.