my check engine light is on

10

Asked by dmb1987 Aug 08, 2012 at 04:19 PM about the 2000 Mercury Mystique 4 Dr GS Sedan

Question type: Maintenance & Repair

My car is throwing codes for both oxygen sensors, so i changed both of them and drove the car for a few days but
the light won't go off and I don't think my cat is bad so what could it be?

9 Answers

60,215

What is both sensors? 2 upstream? 2 downstream? An up and a downstream sensor?

3 people found this helpful.
60,215

Codes were cleared when fixed and its confirmed the same codes are still there? The only codes were the o2 sensor codes? If the cat was bad the downstream would be the only one showing problems. What were the codes exactly?

10

I only disconnected the battery when i installed the 2 sensors, but i'm not sure if that clears it. Before i did the work, the diagnostics codes were "upstream bank 1 and downstream bank 2

60,215

Were they saying rich or lean? Or insufficient flow? Have them checked again and see what they are. Downstream bank 2 leads me to belive there are 2 cats, one on each bank. Is this true?

10

No they didn't say rich or lean or insufficient flow, it said heated something bank 1 and the same for bank 2. The car has only 1 catalytic converter

60,215

Maybe check the wiring. If the engine light is on for the same 2 codes then it could be wiring. If its on for just the downstream one then the catalytic converter is probably dead. If an upstream on goes bad it can make the car run rich and poisen the catalytic converter, and when it goes bad the downstream sensor can trow a code because its not reading what it expects.

10

I think I found the problem, the wires for the upstream sensor were all cut. I think the car had mice living under the hood at some point, so I reconnected the wires and wrapped it all in electrical tape and i'm pretty confident that I fixed this annoying problem! Thanks for your input, I really appreciate it.

Your Answer:

Mystique

Looking for a Used Mystique in your area?

CarGurus has thousands of nationwide listings and the tools to find you a great deal.

Postal Code:

CarGurus Experts

  • #1
    gjm7403
    Reputation
    580
  • #2
    Kirk Sanichar
    Reputation
    400
  • #3
    jb84
    Reputation
    280
View All

Find great deals from top-rated dealers

Search

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.