# B14 is throwing codes p0135 and p0142



## crazy101101 (Jul 10, 2002)

Hi Everyone,

I have a 98 Nissan 200sx. 

It runs fine, but every now and then if I stop at a light, it will idle down to about 500 rpm. Other times, if I stop at a light, it would not idle down below 2000 rpm. the ECU is giving me the codes p0135 and p0142. Then timing checks out ok. I replaced both sensors and checked the wire harness. It all looks good, but I still gets these codes.

Does anyone have any ideas?


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## smj999smj (Jan 1, 2006)

Are you sure about the P0142? While typically a rear O2 sensor heater code, I do not show it as an available code for 98 200SX's. P0141 would be an available code for a rear O2 heater code..

The P0135 is a front O2 sensor heater circuit code. Usually when this code occurs, it's due to a broken heater element inside the heated O2 sensor. Since you've already replaced the sensor, you either have a circuit issue or a bad new sensor. Check 10A fuse #18 in the fuse block and make sure there's power through it with the key "on." If that's good, unplug the front O2 sensor and check for power at the brown/yellow wire with key "on." If that's good, check the resistance of the O2's heater element (brown/yellow & orange wires of sensor's harness); it should be between 2.3-4.3 Ohms at room temperature. You should also NOT have continuity between the center (white) wire of the sensor's harness connector and either the orange or brown/yellow wires. If you are good at this point, you'll need to, with the front O2 sensor and the ECM unplugged, check the continuity of the orange wire from the harness connector to the ECM connector pin #115 and also make sure there is no continuity to ground. If all these are good, the the only possibility left would be a bad ECM. 

The O2 sensor heaters should have nothing to do with idle issues. That sounds more like a faulty IACV-AAC valve. You could try cleaning it out with carb cleaner and then adjusting the base idle per the FSM procedure before replacing it.


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## crazy101101 (Jul 10, 2002)

Thanks smj999smj. P0141 was the code on the front sensor. The fuse blew out,so I changed that one out, and the Rear O2 then started to throw a Hi Voltage signal (can remember the code right now). So I exchanged the rear O2 and the problem was solved.


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