Question about 1998 Jeep Cherokee Grand 2WD
Ok, I have a '94 Jeep Grand Cherokee and the engine light came on yesterday. I tested it using a OBD scan tool that I have and it gives me the trouble code #52. Using the included software and Haynes manual it says "Oxygen sensor signal input indicates rich air/fuel ratio condition during engine operation." Question is, what are the possible causes that would be triggering this code. I have done extensive searching on the internet with no help. I also did testing using a digital multimeter on the MAP sensor, the Air Charge Temperature sensor, and the Throttle Position sensor(TPS) and all were within limits EXCEPT the TPS. It was off just a fraction in the voltage allowed but that should send it's own signal, shouldn't it? I have not checked the O2 sensor yet but will, that is suppsed to throw it's own signal too I thought.
The tps could cause the pcm to think the throttle is open further than it really is, adjusting injector pulsewidth to compensate. but. the 02 would see the rich condition, the idle would suffer and the idle air controller would open to compensate. all technical discussion aside, you need to check the 02 sensors output voltage while running. backprobe the output and make sure you're not getting over 1 volt and that it dances from about 200mV to 800mV at a high enough rate that your DVOM has a hard time keeping up with it. If you get a steady voltage, chances are the 02 sensor is shorted inside to either the ref. B+ or the heater B+. If it's not switching and the voltage is high, unplug it and check for voltage in the signal wire of the harness. could be a wiring issue before the 02 as well.
Posted on May 14, 2008
I had the same problem as soon as i change the o2 sensor the problem was fix hope it helps
Posted on Mar 28, 2009
Also check the engine (Coolant) temp sensor,,this is how the PCM knows if the fuel mixture needs enrichment ,,a False Reading,,and you have on overly rich
Posted on Nov 14, 2008
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