mswenso1

OK, so I have a 2000 4runner, supposedly from Arizona, that has a CEL. I pulled the code with an OBD II scan tool and it said p0125 insufficient coolant temperature for closed loop fuel control, here is my issue...

I have searched and it seems it could be a couple of things:
1) A/F sensor
2) o2 sensor
3) sticky thermostat
4) low coolant

My question is, how should I go about this...I don't have any other codes and after I cleared it, it took a while to come back on (it came on while I was on an on ramp to the highway). Also, how would I find out if my 4runner was originally a Calif. Emissions vehicle. I was told it only had one previous owner but who knows?

Thanks for the help....

obscurotron

There should be a sticker under the hood that says whether it's a 49 state or CA emission certified vehicle.

If you can beg or borrow something like a BR-3 or a ScanGauge/ScanGauge II, hook it up and find out your operating coolant temp. If it's actually low, I'd start by swapping in a new Toyota thermostat. Doing this will require you to drain some coolant, so you can change + top that off at the same time.

While it *could* be an o2 sensor, that would be last on my list. It's also possible that if it was an AZ truck, the PO ran it with NO thermostat (bad, bad idea).

mswenso1

Sweet, thanks for the ideas