Getting O2 Error Codes
 

Hi Folks, I have a 1996 XJ6 that is getting check engine error codes every few days and my son (who owns the car) says it's been running a little rough. The codes are:

P1191 O2 Sensor Heater Circuit Open - Hardware Fault

P1192 O2 Sensor Heater Circuit Shorted

P1194 O2 Sensor Heater Circuit Resistance Fault


I'm no mechanic. I'm guessing a bad O2 sensor (whatever that is) or maybe a wiring issue to that sensor. Any other ideas? And where on the engine might I find this sensor It's a 4.0 engine?

Thanks for any help you can give!!

Bobby

The O2 sensors measure the amount of oxygen left over after cylinder combustion , This in turn regulates how mush fuel is injected into the cylinders so they will not be rich or lean mixture ( referred to as fuel trim as a % on modern cars )

The heaters are used to heat up the sensing membrane to operating temp so it can read the O2 before the exhaust gasses can

The sensor membrane will not read at cold temps until heated up

The oxyegen sensors on the X300 are different as they are Titanium based so they generate a changing resistance and do not generate a voltage like the more commonZirconium sensor


See page 36 , 47 , 80 and 129 for a 1996 year

http://www.jagrepair.com/images/Training%20Guides/801S%20-%202000.pd

There is a fuse # 14 / 10 amp RH egnine fuse box for the heaters and a connector located below the wiper fluid fill cap as Papa Indy - 61 pin 12 ( White / Green wire ) , this connector gets corroded and is common

At the 4 wire sensor connectors that also get corroded there are 2 wires to the individual sensor heaters and they will read the same resistance

The 2 wire colors are Blue / Brown for the fwd sensors ( Blue / Pink for the aft sensors ) and White / Green and are the same for each 4 O2 sensors

The easiest sensors to get to on the sensor connector are behind that Papa Indy - 61 connector

Do not cross connect these 4 wire sensor connectors when putting back together as both will fit either way

Bosch # 13789 is a connector ready replacement for the OEM Denso brand

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WOW. That's a lot of great information! Thank you Lady P. I've gone in and checked most of those connectors. So far they look pretty clean (see pics). I haven't checked the rear connectors (looks like they're on the firewall behind the engine?). They are covered with old oil and dirt and could perhaps be the issue I suppose if any of that leaked into the connectors. I'll keep looking. I'm hoping re seating and/or cleaning the connectors might clear the problem. I'm sure I'll have some more questions after I go through all the posted info. On a side note, it appears I need new hood struts. I went into the garage to retrieve a few tools and the wind slammed the hood down and it broke the plastic shroud on the top of the motor (last pic). I had laid a screwdriver on top of it. Can someone tell me the technical name of this part? I'll have to go shop for a replacement.

Thanks again!

Bobby

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Remember to not cross connect the 4 wire connectors

Clean the ground studs on the back firewall as these are the shield grounds including the ones that protect the very sensitive sensor return signals

On the ECU connectors ............

See page 57 for normality aspirated North American 1996

http://www.jagrepair.com/images/Auto.../jagxj1996.pdf :icon_dance-disco:

Look at sockets Red 6 , 7 , 8 , 11 , 16 , 18 , 19

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There is a couple of those plastic fuel rail covers in KC

Editing