Have code P2238 - what could be the cause ? - 2003 Toyota Tundra

The main problem looks like P0306 which is a missfire on #6 cylinder. P0300 means random misfire so you may have another cylinder misfiring. How old are the plugs?
P0031, P0430 and P2238 all are related to the O2 sensors on bank 1. Which is probably caused by the misfiring of the spark plugs.
I would have the spark plugs changed first. Erase all the codes and then see what happens.

Most of the codes for those readers are not in the book/manual. Only the common ones are. You can search online at the readers website or just enter the code number and usually you cna find the issue easily. I don't even know where my book is anymore. I just plug it in and then hop online. its so much faster.
You can buy a new one:

Have the following checked for proper operation: Mass Airflow sensor (its located on the air filter box), oxygen sensors. If ok, I would recommend having the wires checked for possible damage from rodents biting on them.

Well, there are a couple things going on here.
The code P0500 is a problem with your Vehicle Speed Sensor "A"
This can be caused by a couple things, however there is a software update available for your vehicle and if your computer has not been programmed with the latest update, I would not waste any time or effort on this code until it has.

Technical Service Bulletin # T-SB-0341-09 Rev 1

The other codes (P2238 and P2241) are for your Air-Fuel Ratio Sensors. P2238 is for the upstream Bank 1 sensor and P2241 is for the upstream Bank 2 sensor.

NOTE: The code description on your generic OBD scanner may say "OXYGEN SENSOR" or "O2S". but it is very important to understand that these are "AIR-FUEL RATIO" sensors - they do not work the same as a typical oxygen sensor, although the computer uses the data from these sensors for the same purposes.

These codes are pretty vague. They can be caused by either "open" or "shorted" AF+ or AF- circuits, or they can be caused by either "open" or "shorted" AF Sensor Heater circuits. Most of the time, these codes are caused by failed AF sensors. HOWEVER, since you have codes for BOTH sensors at the same time, it would be VERY WISE to verify the circuits for these sensors before replacing them - you may find just ONE shorted or open wire causing BOTH of these codes.

I personally have had really bad experiences with trying to replace these sensors with aftermarket sensors. I highly recommend that if you are going to replace them, get the parts from the dealer. They are also EXTREMELY expensive in comparison to regular oxygen sensors, so that is another reason for proper diagnosis before replacing them.

P2111 - Throttle Actuator Control System Stuck Open.
P2112 - Throttle Actuator Control System Stuck Closed.
P2238 - O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 1



For the P2111 & P2112 you will need to replace the throttle body this can be pricey since the TAC is built into it. Try cleaning it good and see what happens. This can also trigger the P2238 code if its dumping fuel.
For the P2238 check the connections on the o2 sensor or replace the upstream o2 sensor that should correct it.

Code # p2238 is for the air fuel sensor,you may have a bad sensor the one in the exhaust manifold.

This can be caused by many things. Air/Fuel Sensor is faulty;Short in the A/F Sensor Circuit; EFI Relay; ECM. Hopefully it's just the A/F Sensor as all you'd need to do is to change it. The A/F Sensor is located just before the catalytic converter. If it's the EFI or the ECM, then that will be costly

P2238 = "O2S 1/1 positive current ckt low"

check O2 sensor for degraded performance or wiring to O2 sensor

p2238 is the oxygen sensor bank 1 sensor #1 which is up stream in the exhaust manifold. My manual is showing that the current control crcuit is low. p2245 is the same sensor, showing that voltage circuit is low. Replacing this sensor should fix the problem.

Look the code means: pumping current low