Check Engine Light

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Jun 6, 2005
Mount Holly, Vermont
when ever it gets cold then warms up a lot i get the CEL on. I have had the code pulled and its for a Cat. but once it is warm for a day or two it never comes back on. anyone have any idea what the issue is? could it be an O2 sensor? Im not looking to replace the cat, as i was quoted over 800.
By "cat" I assume the O2 sensor after the cat is indicating bad. It could be the sensor or the cat. I bought a laptop based OBDII reader that can graph the outputs of the O2 sensors, that might show if your O2 sensor is running crazy or flatline. The sensors have heaters in them for when the exhaust is too cool for proper readings, like at idle. It could be the O2 sensor heater is failing.
If your LC is throwing an intermittant catalytic convertor code, then likely that is what your problem is or is becoming. Before long it will likely stay on.

If your problem were an O2 sensor or and O2 sensor heater (assuming the truck is equipped with same) the on board diagnostic computer would throw codes specific to those problems. One of the rear O2 sensors is picking up, intermittantly now, exhaust gas components that indicate a dying catalytic convertor.

We own and I operate a Georgia emissions inspection station. Tens of thousands of inspections worth of data points.

I wish I had better news for you. Shop around for cats. The OEM's last much longer, and they are therefore more expensive. The after-market units will get you by for a while, but tend to give up after a year or two. Give CDan a shout to see what he might be able to do for you with a factory item, then compare. Any competent muffler shop should be able to install a replacement for you.

Users who are viewing this thread

Top Bottom