MIL light, P0054 code, help!

SHELLY369

MEMBER
2005 FORD FOCUS
140,000 MILES

The MIL light is on, after being given the 54 code, and advice to replace the sensor, we replaced the downstream sensor with an OEM part. The light still comes back on after only a few miles. After re-checking with an OBD scanner, we're getting the same code, but now are being told it's something between the sensor and the computer. Not the actual sensor itself. The fuses are fine, the lower sensor is new and fine, what would be the next logical thing to check to get this darn light to stay off? My daughter just bought this car and can't get it registered without emissions. (Will they even check emissions with the light on?) Any help is appreciated.

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

P0054 FORD - HO2S Heater Resistance Bank 1 Sensor 2 Could be an open or short oxygen sensor harness or poor connection. You will fail the emission testing with the CEL being on-

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Monday, February 27th, 2012 AT 9:58 PM

SHELLY369

MEMBER
2 POSTS

Thx. I know it will fail emissions, I'm just trying to figure out the next step. The connections to both sensors seem to be fine, I'm wondering if maybe one of the wires in the upstream (the one not replaced) might be loose inside the harness. Also, do you know anything about the relays? We haven't checked to see if they're all good or not, but 12, 13 1nd 14 aren't even in the box, are they unused or should they be there?