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Stock JK TechBulletin board forum regarding issues with OE (original equipment) components of the Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X) such as factory suspension parts, engine, transmission, body parts, interior fixtures and the on-board computer.
Bank 1 is passenger side, sensor 2 is downstream of cat -- Is that what you replaced?
The code means the heater (for the sensor) has low voltage, which is circuit K299 in the drawing below. The resistance of the heater (pins 1 & 2 in the drawing) is supposed to be 2 to 30 ohms at 70 deg F ambient. Since the code is heater voltage low (at the PCM) it would take a low resistance (shorted) heater, a short to ground on K299, or a bad PCM.
I got the right sensor...thanks for the info. I will try tracing the wires back looking for a short.
Would a failing battery cause this intermittent problem?
I got the code to clear after 3 'drive cycles'.
Just for fun I turned on every electrical draw I could think of and started it...during cranking the voltage on the ECU dropped to 10.8 (according to my scan tool) and the code came back.
3 drive cycles, it's gone again
I got the right sensor...thanks for the info. I will try tracing the wires back looking for a short.
Would a failing battery cause this intermittent problem?
I got the code to clear after 3 'drive cycles'.
Just for fun I turned on every electrical draw I could think of and started it...during cranking the voltage on the ECU dropped to 10.8 (according to my scan tool) and the code came back.
3 drive cycles, it's gone again
I got the right sensor...thanks for the info. I will try tracing the wires back looking for a short.
Would a failing battery cause this intermittent problem?
I got the code to clear after 3 'drive cycles'.
Just for fun I turned on every electrical draw I could think of and started it...during cranking the voltage on the ECU dropped to 10.8 (according to my scan tool) and the code came back.
3 drive cycles, it's gone again
10.8 V during cranking is OK, but grounds and bad connections, especially intermittent ones, can have strange side effects. This is sounding like an intermittent problem, and I think you're on the right track to check the wiring from the sensor to the PCM first. If I remember right the wiring goes up and over the bell housing -- very hard too see up there. Has the transmission been out recently, any work done that might damage wiring?
Just thought of something -- What brand of sensor did you use? If it's Bosch, you may want to try a Mopar or NTK instead.
Side note: The PCM may be comparing the voltage at the pin connected to K299 with the three other O2 sensor heaters, as well as fixed alarm points. If it works this way, mixing O2 sensors from different brands may not work so well. Bosch sells a lot of O2 sensors, but they are the cheapest, and feedback isn't 100% positive with the JK.
Last edited by Mr.T; 05-24-2018 at 05:00 PM.
Reason: added side note...
Yeah. The transmission was rebuilt in January...I have put about 5000 miles on it.
it is an ntk sensor.
I'll see what I can see around the top of the bell housing.
There's a sheet metal support for the wiring that uses two of the upper bell housing bolts on the passenger side. If that wiring support isn't put back carefully the wiring could get pinched during install, or eventually rub insulation if it's not properly installed.
05-24-2018, 09:18 AM
O2 sensor pains P0037
