I have an '03 F150 supercab - 4.6l - manual trans - 4x4 - recently replaced the air filter.

I have the P0135 - "o2 sensor heater circuit for bank1 / sensor 1" and a P1131 - "lack of HO2S11 switches, sensor indicated lean". If I am reading correctly, both of these codes are referring to the same sensor.

I have done some searching of the threads here, and I have checked the O2 sensor fuse (#23) and it's fine. The next step, as I understand from my research, is to check for vacuum leaks, but what has me thinking it's not a vacuum leak is that the truck runs fine. Starts well, idles fine, great acceleration, no stumbles, doesn't die.

All of which leads me to believe it's simply the sensor that has gone bad. I'm the original owner of the truck and the sensors have never been replaced.

Is there anything else I should check before I haul off and replace the sensor?

Thanks in advance!

 

How many miles on the truck?

o2 sensors are consumable items. I replace mine in all my gas o2 equipped machines 60-80k miles or ~1,500 hours.

While you are at it, check the back pressure of the exhaust system to make sure your converters aren't clogged, which can also result in a lean condition.

 

A code P0135 may mean that one or more of the following has happened:

O2 Heater element resistance is high
Internal short or open in the heater element
O2 heater circuit wiring high resistance
open or short to ground in the wiring harness

Possible Solutions

Repair short or open or high resistance in wiring harness or harness connectors
Replace oxygen sensor (cannot repair open or short that occurs internally to sensor)

Read more at: https://www.obd-codes.com/p0135
Copyright OBD-Codes.com

Is the second code P1131 or P1135?

 

The truck has 148K miles - thanks.

 

The second code is P1131. I did a cursory inspection of the wiring and it looked ok. Probably should take a detailed look
Thanks!

 

Heater circuit only.
Check for voltage at the sensor socket with a meter.
If it's there with the 'key on', then check sensor resistance to verify it's the sensor.

 

Thanks - Guess I should go buy a meter ;-)

 

The only thing in common with those 2 codes is the sensor or wiring.

 

Completely ancedotal, but I had a p0135 in my lancer. Replaced the o2 sensor with some $10 no name sensor from ebay, and the light has been gone for over 50k miles.