2007 Tacoma 2.7 throwing C1241 & P0138 Codes At Same Time

Just purchased a 2007 Tacoma with 235k miles and I'm trying to work out some bugs. Had the codes cleared this morning and about 15 miles later it lit up the CEL and I immediately (less than .2 mi) pulled into the auto parts place and had them pull the codes. Both C1241 & P0138 were showing.

Has anyone seen these two being thrown at the same time? Possible causes I should look at first?

 

Did you buy the truck from a dealer? If so, go back to them and have them fix it. I think you should at least a 30 day warranty with a dealer on a used car

 

Nah private purchase

 

CODE: C1241, Low Battery Positive Voltage

DESCRIPTION

If there is a problem with the brake actuator (skid control ECU) power supply circuit, the skid control ECU
outputs a DTC and prohibits operation under the fail safe function. If the voltage supplied to the IG1 terminal is not with in the DTC detection threshold due to malfunctions in parts such as the battery or alternator circuit, this DTC is stored.

DTC Detecting Conditions

• At vehicle speed of 2 mph (3 km/h) or more, voltage at IG1 terminal remains at 9.5 V or less for 10 seconds or more.

• When solenoid relay ON, voltage at IG1 terminal 0.5 V or less, and contact of relay OFF for 0.2 seconds or more.

• When voltage at IG1 terminal 9.5 V or less, voltage of speed sensor power supply decreases for 60 seconds or more.


Trouble Areas

• Battery

• Charging system

• Power source circuit

 

P0138, Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)

DESCRIPTION

HINT:
Sensor 2 refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far
from the engine assembly.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC (Three-Way Catalytic Converter) is used. For the most efficient use of the TWC, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel level. For the purpose of helping the ECM to deliver accurate air-fuel ratio control, a Heated Oxygen (HO2) sensor is used. The HO2 sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low). When the air-fuel ratio becomes lean, the oxygen concentration in the exhaust gas is rich. The HO2 sensor informs the ECM that the post-TWC air-fuel ratio is lean (low voltage, i.e. less than 0.45 V). Conversely, when the air-fuel ratio is richer than the stoichiometric air-fuel level, the oxygen concentration in the exhaust gas becomes lean. The HO2 sensor informs the ECM that the post-TWC air-fuel ratio is rich (high voltage, i.e. more than 0.45 V). The HO2 sensor has the property of changing its output voltage drastically when the air-fuel ratio is close to the stoichiometric level. The ECM uses the supplementary information from the HO2 sensor to determine whether the air-fuel ratio after the TWC is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the HO2 sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air-fuel ratio control.


DTC Detecting Conditions

• High voltage (short): During active air-fuel ratio control, following conditions (a) and (b) met for certain period of time (2 trip detection logic)
(a) HO2 sensor voltage output 0.59 V or more
(b) Target air-fuel ratio lean

• Extremely high voltage (short): HO2 sensor voltage output exceeds 1.2 V for more than 10 seconds (2 trip detection logic)


Trouble Areas

• Short in HO2 sensor (bank 1, 2 sensor 2) circuit

• HO2 sensor (bank 1, 2 sensor 2)

• ECM internal circuit malfunction

 

Is there any reason both of those would be thrown at the same time? Seem pretty dissimilar.

 

I don't see any correlation between the two codes.