I had the P1131 code come up on the computer on my truck. It is a 1997 Ford F150 ext cab 4x4.

The issuse im having would be the O2 Sensor i know this already. Heres the thing. I have a "load" injector like most fords so i put injector cleaner in the first tank. This time i put seafoam in to do a little more cleaning. Could the sensor read lean because of the seafoam. If so what should i do clear the code and run the tank out then see what happens or replace the sensor?

 

I'd run the seafoam out of it before replacing the sensor. No need in screwing up a new sensor with that oil you just dumped in the gas. But the likelihood of you having to replace it are high.

 

Oil? I have never had an issuse with seafoam. I have put it in almost every car truck bike i have ever owned. Why so agenst it?

 

It's snake oil + it can really screw things up, depending how you use it. If you add it to a tank of gas, your not doing anything as far as cleaning. Petrol has better cleaners already in it, your just down grading an already good thing. If you suck it thru a vac line, you can ruin your sensors, converters and cause hydro-lock.

You can use to assist cleaning by hand. Like the throttle body and elbow, but I wouldn't run that stuff thru an engine. I've seen what can happen and what doesn't when doing so.

A Motorvac or BG service from the dealership cleans the best. The only off the shelf product that works is AutoRX.

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P1131 Lack Of HO2S11 Switch - Sensor Indicates Lean

FRONT SENSOR SIGNAL
The Front sensors are tested continuously for switching during Closed Loop operation provided the Conditions are met. Excessive time between switches, or no switches, indicates a malfunction. Since the lack of switching could be caused by fuel trim shifts as well as a sensor malfunction a stored DTC indicates whether the sensor was always indicating lean or rich when it stopped and if the Fuel Trim was at max.

Where Lack of Switch DTCs are recorded the LT Fuel Trims should be watched closely - if these show well into the negative or positive at idle they could be caused by an air inlet leak or a faulty Fuel Pressure Regulator - meaning that the fuelling has not changed rather than the HO2S not detecting it. Before changing front HO2S sensors Pressure Sensor and Sample Scan first - particularly if there are any starting issues.

DTCs

P1130 - Lack of Switching - Fuel Trim at Clip (no further trim available) Bank 1

P1131 - Lack of Switching - Sensor Indicates Lean, Bank 1

P1132 - Lack of Switching - Sensor Indicates Rich, Bank 1

P1150 - Lack of Switching - Fuel Trim at Clip, Bank 2

P1151 - Lack of Switching - Sensor Indicates Lean, Bank 2

P1152 - Lack of Switching - Sensor Indicates Rich, Bank 2

NOTE: In extreme cases where the Front sensor(s) is not switching the Closed Loop operation is never achieved - the system stays on Open Loop fuelling and the DATA page on the Vehicle will show this. ~ LOOP at PID# 1103 b6 on the Enhanced Data will show OPEN.

Sensors OK
The following sensors have been checked before this sequence and have passed.

IAT - Inlet Air Temperature
ECT - Engine Coolant Temperature
MAF - Mass Air Flow Sensor
TPS - Throttle Position Sensor

Entry Conditions
The test will be carried out when the engine load is between 20 and 60%, it is at least 180 minutes since start up. The exhaust temperature is assumed to be 800° C

That said, changing both forward O2's is recommended. Seeing how 135/155/141 or 161's usually indicate a wiring/connector problem.

 

Don't overlook that the injectors could be gummed up. They are easy to remove and take a look at.