NISSAN ALTIMA 2001

I got the code from AUTOZONE, P1126.
1) But i could not find the code on the repair manual, i donot know why.

2) Is ECM code universal or each car has its own code?

This is the result of my research on P1126.

3) I had coolant leak from near the waterpump. But i am not sure where though. What do you guys think i should do? Does anyone know where the thermostat is located?

P1126 – (2000-2001) Thermostat Function

there’s either a leak in the seal, the thermostat could be stuck open, or the coolant temp sensor is bad.

you could have a faulty engine coolant sensor. before the engine goes to closed loop and uses the oxygen sensor as a guide to fuel/air mixture, the computer uses various other sensors to determine the mixture ratio. the cooler that an engines coolant temperature is, the cooler the engine is , so the mixture is just a hair more rich to get the engine up to operating temperature. the manufacturer specific code has to do with that sensor, a poorly operating thermostat or low coolant at the sensor level, making it unable to sense the true temp of the coolant.

I replaced the thermostat and the problem went away.

At the beginning, I was doubtful about it because my Nissan Service Manual does not have this P1126 code. Another gentleman also pointed me to the coolant temperature issue. I noticed for three consecutive times the OBD showed the code after about nine miles of driving and the freeze frame temperature was 160 every time. I decided to change the thermostat.

At our dealer we had some cars with the P1126 code, and replacing the thermostat have take car of the problem, but the possible causes are:

– Thermostat function
– Leakage from sealing portion of thermostat
– Engine coolant temperature sensor

Code P1126 Fuel/Air Ratio Error

Oxygen sensor had shorted out. They replaced charging $241.66 for part, plus $99.00 for labor. Later learned part could be purchased aftermarket for about $19.00 and the repair is basically unscrewing one sensor from the exhaust pipe and screwing in a replacement. Also learned from Bosch that life expectancy of sensor should be approx 100K.