How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Chris (aka- Moose) Your Own Question
Chris (aka- Moose)
Chris (aka- Moose), Mercury Technician
Category: Mercury
Satisfied Customers: 1962
Experience:  16 years experience with Mercury
Type Your Mercury Question Here...
Chris (aka- Moose) is online now
A new question is answered every 9 seconds

I have a 2000 mercury grand marquis that sets the check

Customer Question

i have a 2000 mercury grand marquis that sets the check engine light and codes out problems with the emission system. using my live data on my scanner the # ***** o2 sensor has erratic reads going down the road. it reads from ooo to 800 but does not ever stay
within a 100 differential . before replacing would like to know if it could the pcm or the o2 sensor
Submitted: 1 year ago.
Category: Mercury
Expert:  HDGENE replied 1 year ago.

Hello, depends on what code(s) are setting and if you are having an issue with the upstream precat convertor sensor or the catalytic monitor sensor they operate differently

Customer: replied 1 year ago.
the precat sensor is the one that is giving bad readings number 2 on code readerthe
Expert:  HDGENE replied 1 year ago.

Ok the drivers side(bank 2) upstream oxygen sensor is not reading properly. its setting a code so the check engine light is on. Whats the code P0174/lean. rich code? heater circuit. need some more information please.