Toyota Camry P0171 P0125 P1135 Emission Failure Codes
Air Fuel Ratio Sensor
Many codes, one problem.
Oxygen sensor failures are common to all cars not just Toyotas. But Toyotas present different codes that you might not expect for this common problem.
When a car has the 300 dollar oxygen sensor (California emissions) we call it the air fuel ratio sensor. Check with Toyota dealer by VIN number to verify which type you have. An air fuel ratio sensor is not interchangeable with a regular oxygen sensor even though they look the same.
P0171 System Too Lean. This code will set when an air fuel ratio sensor gets lazy.
P0125 Insufficient Coolant Temperature For Closed Loop. Sounds like a bad thermostat right? No, on Toyotas its our air fuel ratio sensor taking too long to get active.
P1135 Air Fuel Ratio Sensor (Bank 1 Sensor 1) Heater Circuit Malfunction. The heater in the air fuel ratio sensor is drawing too much or too little current.
Amazon sells the Bosch 13733 air fuel ratio sensor for about 113 dollars which is the lowest price I have been able to find anywhere. This sensor works well on these cars.
More by this Author
The above diagram shows the serpentine belt routing picture for the Chevy Impala LTZ 3.9 engine. You can click the image for a full size view and print it out. Looks like you found a better place to publish and share...
Here is a drive cycle that works well on Toyotas when trying to set the readiness monitors to pass an emissions test. I developed this myself from trial and error. Fuel tank at 1/2. Engine cold start idle for 10...
It is possible to cheat an emissions test to conceal catalytic converter faults. Oxygen sensors behind the converter can be tricked.