'97 Camry 4 cylinders Check Engine Light

This is more fact that there should be some sort of class for women in high school and college about basic auto care because sometimes my girlfriend doesn't cease to amaze me.

So I go to make the routine oil change on the car today and notice that the check engine light is on. I ask my girl how long shes been running with the little light on and she responds "Oh for about two months or more now."

I swear, sometimes I just don't know how people don't realize that the little light might be something important that needs to be fixed. She figured that since the car was still running fine, that it must not have been anything important so she didn't tell me.

Anyways, after making the oil change and getting everything back together I head over to Autozone so I can rent the machine to check the codes and I go to check the codes hoping to to only find one or maybe at the most two but I get stabbed in the heart when 4 pop up.

Here are the 4 codes that were in the system, any help on what may be the problem will be greatly appreciated.

P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control

P0171 System too Lean (Bank 1)

P1130 Air-Fuel Sensor Circuit Range/Performance

P1133 Air-Fuel Sensor Circuit Response Malfunction


Any input that the experts on this board may have (Brian R., Toysrme) I would love to know how to go ahead and fix one or all of these problems. Thanks a lot for your time.

If I were a betting man, I'd bet you need a new HO2 or A/F ratio sensor (the one nearest your engine - right in front, not the one after the cat. converter). Bring your VIN to a Toyota dealer and get the correct part number. Then, use that part number to buy a sensor. I would buy one from Toyota, but there are probably other good brands.

I'm with Brian.
Welp I'm fairly sure the coolant sensor is shot.

When the coolant sensors read cold during warm-up, the engine runs in open-loop (No o2 sensor) mode until they have come up to temp.
The colder the coolant sensor reads - the richer (more fuel) the engine will use. Up to a theoretical maximum of 6% more fuel (Not that much), and practical like 4% more fuel.

The o2 sensor is probably dead as well if it's reading lean. The conditions the car *should* be running in if the coolant temp sensor is reading cold coolant is rich (more fuel), not lean (less fuel).

AFA the ECU saying the o2 responce time is low, it's saying it's taking way too long to warm the sensor up. Depending on the ECU logic, it may be reading only the coolant sensor to see when the o2 is warmed up, or it could be monitoring the o2 heater circuit itself to see when it *actually* warms up.


Check the coolant & o2 sensors. Download that '97 FSM I posted for an ES 300. it'll be v6 only, but it should go over the coolant & o2 testing proceedures & the general specifications of those 2 parts should match your i4 engine.