DTCs P2197 & P2198? | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

DTCs P2197 & P2198?


Moderator Emeritus
May 26, 2009
Reaction score
City, State
Greenville, SC
Year, Model & Trim Level
00 Sport FI, 03 Ltd V8
2003 Explorer Centennial (Ford 100 year anniversary Limited) with 4.6L V8.
Began dying at closed throttle so I replaced spark plugs and then IAC valve. At half full fuel tank added bottle of Techron fuel injector cleaner. Tank now at quarter full. Engine no longer dies but still rough idle. Current DTCs:

P0152 - O2 Sensor Circuit High Voltage, Bank 2 Sensor 1 (too rich)
P2197 - O2 Sensor Signal Biased/Stuck Lean (Bank 2 Sensor 1)
P2198 - O2 Sensor Signal Biased/Stuck Rich (Bank 2 Sensor 1)

No misfire codes detected.
I added the fuel injector cleaner thinking that an injector on bank 2 (driver side) might be sticking (sometimes open and sometimes closed) resulting in the conflicting too lean and too rich DTCs for the same O2 sensor. However, burning a quarter tank of fuel should have been enough for the Techron to do its job and no misfires makes me suspect there is something else amiss. I guess the next step is to check the wiring to the O2 sensor and the sensor electrical connector. I know the heater wires are still connected since there is no associated code reported. I'll also clean the exterior of the O2 sensor since the atmospheric vent could be clogged but it looks pretty clean.

The sensor is probably more accessible than the connector.

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

If it has never had any trans work and the wires haven't been disturbed I'd assume the wiring is ok. I haven't seen any wiring issues to the o2s unless someone has fiddled with it.

I'd just swap in a new o2 for "testing". You can get the oem ones on rockauto for less than $80 shipped.

I tried to reach the O2 sensor connector from the top reaching down between the back of the engine and the firewall but couldn't find it. So I raised the driver side up using my hydraulic jack and supported the frame with jack stands. After crawling underneath and following the O2 sensor wire with my fingers I was able to release the connector. Using my 15 inch adjustable wrench and "tapping' the end of it with my 4 pound hand sledge I was able to loosen the old O2 sensor. Then I used a 22 mm open end offset wrench to unscrew the sensor. The insulation on one wire is cut on the bend near the end of the sensor.

Notice that the new Bosch sensor has an accordion strain relief. It came with anti-seize compound on the threads. Its a genuine Bosch (in original box) 15664 I purchased on eBay for $28. The electrical connector is not keyed so it can be used in any position (left or right upstream or downstream. All of the sensor ports are on the end instead of the sides and end.

After installing the new sensor I couldn't reach far enough to push the connector into it's mate because the automatic transmission cable/housing is in the way. I'll have to remove the cable support mounting bolts in order to push the cable aside so I can reach the connector.

I was able to lay on top of the fender reaching down between the back of the engine and firewall and pull the O2 connector into its mating connector. The mating connector is mounted vertically instead of horizontally as shown in post #1. When I was under the vehicle yesterday I noticed an abrasive indentation in the transmission cable housing.

The cable protective sheathing is fairly thick but just to be sage I made a spiral cut in a length of tubing and threaded it onto the sheathing for additional protection.

In a couple days I'll clear the DTCs and then see if they are reset after a few drive cycles.

Replacing the O2 seems to have corrected the poor engine performance and so far (after two short drives) there are no DTCs. It idles so much better and pulls well at light throttle from idle. Thanks for the encouragement to replace the sensor boominXplorer! I'm so pleased with the improvement that I'll probably replace the passenger side O2 sensor. It's probably due after 14 years and 185K miles.

Good to hear!! I often find damaged O2 wires working on vehicles with prior transmission work or engine replacement. Usually they get beat up or wires chaffed when everything is in the "lining up" process.