CHECK ENGINE LIGHT ON- WHAT DOES THIS MEAN?

I have Digimoto.com software, so I plugged my laptop into my '98 Jeep Cherokee. Software read a high heat reading on the bank 1, sensor #2. In test mode, the sensor read 1.0 or just 1, but didn;t move when I revved it. The other sensor, bank 1, #1, reacted and read .8's etc.

Sorry for the real techie question, just wondering if some gurus know what this means. I believe the reading was also called "generic 0138."

It means your O2 sensor voltage is high.

need a new sensor, or other problems?

Is it throwing a code for the heater or is it throwing a code for the actual sensor?

I've been getting p0138 on and off at random times since about March, and only recently caught it giving more than twice the voltage it should be. FSM calls b/w 0-1V and mine was 2.25V. This is from hooking up a system much like yours (only not on a laptop) and doing digi read outs on it every time the light came on. I refused to replace it untill i could catch it in the act, and like i said, i just recently (about 2 weeks ago) caught it.

I'm going to be replacing the sensor here in the next week or so, that's all I can recommend right now, as i'm not sure if this will fix the problem.

Had the Jeep for 6 months, first time it kicked on the check engine light. Not sure if I understand the heater or actual sensor question. On the software program, both the sensor and the short term fuel trim read 1, with no movement. I'm going to disconnect the battery and see if it clears. Can you help me out with the location of the second 02 sensor?

Paddy Whacker said:

Had the Jeep for 6 months, first time it kicked on the check engine light. Not sure if I understand the heater or actual sensor question. On the software program, both the sensor and the short term fuel trim read 1, with no movement. I'm going to disconnect the battery and see if it clears. Can you help me out with the location of the second 02 sensor?

Click to expand...

Right around your exhaust manifold and another down from there.

#2 would be the one in or just aft of the cat.

Number two is right inbetween the cat and the muffler.

The heater and the actual sensor are two different things, and thus there are different codes that go accordingly. Do you know the number of the code it's throwing? For example mine was p0138. Have you tried turning the light off to see if it comes back on? In my case the light comes on and goes back off once it's sensed so many "no fault" starts, thus meaning it's obviously shorting out briefly to trip the light, and made tracking the damn thing down hard.

When reving the engine (at a constant RPM), sensor #1 should be giving readings all over the place, and sensor #2 should be pretty constant.

The strange part about mine is when I finally caught it giving 2.25V a couple of weeks ago, the light was off, and it has remained off.

I would hold off on replacing that sensor just yet. Do some more tests on it.