Primo

Hey everyone, I have a 2000 4Runner and the check engine light recently came on. I took my truck to Auto Zone to have the codes pulled and this is what I got:

P1135 - A/F Sensor heater circuit malfunction and
P1130 - A/F Sensor heater circuit malfunction

They may have been worded differently.
I did a search and read some threads about those specific codes but did not come away with any clear advice. Is it the O2 sensor or the A/F Sensor or something different.

I supercharged the truck about a year ago and added URD'S fuel upgrade kit as well at the same time. I have not done any tuning to the truck and this is the first time I have gotten any CEL code on this vehicle. The truck has 80,000 miles on it and has never had a sensor replaced. The code did start the day after I got my truck back from being detailed and the URD Calibration unit is located in the passenger compartment up under the rug so I don't know if they may have hit something that could also cause the code. Just looking for some advice. If it's a sensor that I could replace myself, I would prefer to do that. Does anyone know definitively what those two codes point to?

Thanks for your help,

Rob

SEAIRESCUE

I think its the O2 sensor heater. If the sensor is 4 wire it has a pre-heater electrical resistive circuit. The resistive circuit dies over time from the exhaust heat. If you got two O2 sensors, the pre-cat sensor typically craps out first.

My $0.02

Primo

Anyone else?

techno

I had the same codes 2 weeks ago on my 2000 4Runner which has 87000 miles. I replaced the the o2 sensor in front of the cat and that fixed the problem.
In toyota language, the o2 sensor and the a/f sensor are the same thing.

86tuning

Some Toyotas use AFR sensors (Air-Fuel Ratio, or wideband sensors) and others use normal 02 (narrowband) sensors.

However, it amounts to the same thing. The ECM detects that the heater circuit current is too small during heated operation = failed heater inside the sensor.

You can check it yourself with an ohm meter. Measure the 2 black wires, and normally you'll see around 10-15 ohms resistance on a good sensor. On your vehicle, it's going to show an open circuit.

The fix is to replace the sensors.

Denso or genuine Toyota sensors are going to give you the longest life and least problems on a stock vehicle.

HTH.

Primo

Thanks, I guess I will go ahead and order the O2 sensor from URD.

Rob