Car Questions
RepairPal is your advocate for car care advice and guidance

Keep getting code 42 on KOER test. Changed o-2 sensor. Shows always rich.

(1990 Ford Bronco)
in Foresthill, CA on October 13, 2013
Trucks been non-op past 6 or so years. Tried inj. cleaner. Checked connectors. Generally seems to run o.k. but still sometimes gets a dirty inj. Don't have a emissions manual or breakout box. Any way to check o-2 sensor with ohm meter?
Ask a Question
Displaying 3 answers & 4 comments
Popular Answer
on October 13, 2013
Full size Bronco? If so which engine?
Sign in to reply
on October 13, 2013
Yeah, I thought that info was there. It's a full size Bronco with a 4.9 L 6,5 speed former Forest service vehicle with 85,000 miles.
on October 13, 2013
Same injector giving the trouble every time? These engines had some connector problem at the injectors. Did you change the fuel filter? How much old gas is in the tank? Don't worry with the code just yet!
on October 13, 2013
Yeah. I changed the fuel filter and the #5 fuel inj. was dumping raw fuel but then cleaned up. I changed it anyway but didn't help.
of Greg's Orange Auto on October 14, 2013
Sign in to reply
of G. T. Service Center on October 13, 2013
Think you have more problems then an o2 sensor. Leaky injectors/pressure regulator. Trying to remember, Warm up engine - test the gry/lt-blu wire and ground. Idle should be 0.1-0.9v, increase engine speed voltage should increase and decrease as rpms drop. If it doesn't work as stated it's probably bad.
Sign in to reply
on October 13, 2013
Thanks,I'll''give it a try.
Get a repair estimate
RepairPal estimates are guaranteed at over 2,000 quality certified locations nationwide.
Or interested in getting a repair? Find a Shop

Similar Questions

View answers to similar questions from RepairPal's community of auto experts and enthusiasts.
every time i drivie my automatic 1990 ford bronco xxl full-size bronco. my oil pressure stays normal when pressing ...
Switch to back window works when i’m pressing the down button and window does roll down. motor works fine but when i ...
Didn't find what you were looking for?