Getting rid of the pesky engine light

Jackson S

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Joined
Mar 15, 2022
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46
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Australia
Hey guys, ive diagnosed my engine light and its coming up with error cod P0133 which has to do with the oxygen sensor. does anyone here know how to fix the issue and diagnose whats actually causing the light to come on?
 
Slow response is usually caused by a lazy or old O2 sensor. It can also come from replacing the OEM sensor with a junk parts store brand.

However, you asked how to ACTUALLY diagnose it. To do this, you need to verify that the signal is slow by looking at graphed data compared to a known good (Bank 2 sensor 1) on an OBD2 Scan tool while making sure the vehicle is in closed loop and RPM is held steady around 2k. If the switching from lean to rich is in fact slow, you should unplug the sensor, and manually drive the sensor lean and rich with an incandescent test light while watching for the manual input on the graphed data for the offending O2 sensor, or, by introducing a fuel source into the intake like propane, brake parts, etc, watching the signals go rich, and then introducing a vacuum leak and watching them drive lean. A few different ways to skin that cat.

All that said.... NTK O2's are cheap. Probably time to replace all 4 anyways.
 
Slow response is usually caused by a lazy or old O2 sensor. It can also come from replacing the OEM sensor with a junk parts store brand.

However, you asked how to ACTUALLY diagnose it. To do this, you need to verify that the signal is slow by looking at graphed data compared to a known good (Bank 2 sensor 1) on an OBD2 Scan tool while making sure the vehicle is in closed loop and RPM is held steady around 2k. If the switching from lean to rich is in fact slow, you should unplug the sensor, and manually drive the sensor lean and rich with an incandescent test light while watching for the manual input on the graphed data for the offending O2 sensor, or, by introducing a fuel source into the intake like propane, brake parts, etc, watching the signals go rich, and then introducing a vacuum leak and watching them drive lean. A few different ways to skin that cat.

All that said.... NTK O2's are cheap. Probably time to replace all 4 anyways.

i sorta understand that. im not a mechanic so can u dumb it down a little bit please
 
This. It's not throwing parts at a problem if it's a maintenance item. O2 sensors should be replaced occasionally anyway.

If 05-06 work in this order-


Sensors

Cats

TSB to get cats off the ASD

PCM

Therapy

Or you can save a lot of money and just go straight to therapy.
 
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I second getting NTK sensors and swapping all 4. Did this recently with an exhaust overhaul and waaalllaaaaa, no more CEL
 
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What would cats have to do with an upstream O2 sensor?

Maybe nothing at all, except they all tend to fail around 70,000 plus miles and usually go hand and hand, and a clogged cat can create heat and damage the upstream sensor.

In the diagnostic process I’ve never been able to rule out the cats entirely myself.

I’m sure you know this but the catalytic converter’s create the change the upstream and downstream centers monitor.
 
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