P0133 & P0153 codes
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Elder User
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From: Winnipeg Canada
P0133 & P0153 codes
I have these codes on my '97 Explorer. Slow response from both upstream o2 sensors. What could cause this? I'm getting decent gas mileage. Just looking for things to check for before I replace them and it doesnt solve the issue.
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Do a forum search for more threads on O2 sensors, there's plenty of info already on here about very similar problems.
One thing I learned the hard way is that if both sensors are bad, it's ALMOST never the sensors themselves!
One thing I learned the hard way is that if both sensors are bad, it's ALMOST never the sensors themselves!
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Joners, a slow response code usually indicates a lazy O2 sensor, but I'd try this before replacing them: Unplug both and squirt the connectors with WD-40 and re-plug. Then clear the codes and drive it. When the MIL lights again, check the codes and see if only one or both return. That should tell you if it's a wiring problem or the O2s are indeed wearing out.
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From: Phoenix
For O2's it is the switch rate. They switch about .45V, higher is rich, lower is lean. Depending on the sample frequency rate of the scanner, you should see high and low reads switch off about every 2-3 seconds. Less than that and you might get the slow response code. Obviously, if there is no switching (stays high or low) you either have a bad sensor of a truely rich or lean condition which would then require more troubleshooting.
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From: Winnipeg Canada
Wouldnt it give a different code then if it were running rich/lean? What else can I check if it's running rich or lean.
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From: Phoenix
Sure. There are about a dozen codes for O2 sensors. But to verify the slow response that you are getting codes for, you need to watch the sensors real time on your scanner. You should be able to watch them individually when the car is runnning. You will see the actual voltages and they need to switch about .45V. Some sources say the PCM should be swtiching high/low 10-20 times per second. Not sure if this is true. my scanner and on a EEC-IV, you have EEC-V, only samples every 1/2 second. I see the O2's swtich about every 2-3 seconds when everything is running right. But your advance computer and a different scanner may show different results. Certainly, if you see them switch just once every 5 or 10 seconds, then they are truely switching slow. Now you have to find out why. Maybe sensors are OK and telling you the truth. So maybe you have a slight misfire and therefore the bank runs towards the rich side as the O2 sees it. But maybe replacing the sensors is all you need to do...this is the fun in troubleshooting.
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Elder User
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From: Winnipeg Canada
It also sounds like I have an exhaust leak. I guess I'm gonna have to hookup the scanner again and see what it's switching at and go from there...troubleshooting is fun...NOT
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sasarrn
Explorer, Sport Trac, Mountaineer & Aviator
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Mar 26, 2015 10:23 AM
