Code P0038

It could be, but it could also be the wiring or harness connector.

Did you use genuine Toyota (or equivalent Denso brand) sensors?

Did you perform all the diagnostic steps in the Repair Manual (more info)?

Do you have Techstream (or another capable diagnostic tool) to read the freeze frame data?

P0038 specifically refers to the bank 1 sensor 2 which is the heated oxygen sensor mounted after the three-way catalytic converter (TWCC). There probably was no need to replace the A/F sensor (bank 1 sensor 1) before the TWCC. It will do no harm to replace it with a genuine OEM sensor, just added and unnecessary cost. If you used a generic aftermarket part, you may have introduced new problems.

The following are excerpts from the repair manual for P0038.

	DTC No.	DTC Detection Condition	Trouble Area
1	P0038	When the heater operates heater current exceeds 2 A (1 trip detection logic)	Short in heater circuit of the heated oxygen sensor Heated oxygen sensor heater EFI M relay (integration relay) ECM

MONITOR DESCRIPTION
The sensing portion of the heated oxygen sensor has a zirconia element which is used to detect oxygen concentration in the exhaust gas. If the zirconia element is at the proper temperature and the difference of the oxygen concentration between the inside and outside surfaces of the sensor is large, the zirconia element will generate voltage signals. In order to increase the oxygen concentration detecting capacity in the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor. When the current in the sensor is out of the standard operating range, the ECM interprets this as a fault in the heated oxygen sensor and sets a DTC.

Example:

The ECM will set a high current DTC if the current in the sensor is more than 2 A when the heater is OFF.

Similarly, the ECM will set a low current DTC if the current is less than 0.25 A when the heater is ON.

	MONITOR STRATEGY
1	Related DTCs	P0037: Heated oxygen sensor heater current bank 1 sensor 2 (low current) P0038: Heated oxygen sensor heater current bank 1 sensor 2 (high current)
2	Required sensors/components	Main sensors: Heated oxygen sensor Related sensors: Vehicle speed sensor
3	Frequency of operation	Continuous
4	Duration	0.5 seconds
5	MIL operation	1 driving cycle
6	Sequence of operation	None

TYPICAL ENABLING CONDITIONS

	All:
1	Monitor runs whenever following DTCs not present	None
2	Battery voltage	10.5 V or more
3	Engine	Running
4	Starter	OFF
5	Catalyst intrusive monitoring	Not operating
6	Intrusive heating	Not operating

	P0038:
1	When the following conditions are met	0.3 seconds or more
2	Learned heater current during heater OFF	Completed
3	Intrusive heating	Not operating
4	Heating is OFF	Less than 0.1 seconds
5	Heater current	2 A or more
6	Time after heaters are OFF	1 second or more

TYPICAL MALFUNCTION THRESHOLDS

	P0038:
1	Heated oxygen sensor heater current	More than 2 A (while supplemental heating is OFF)

	COMPONENT OPERATING RANGE
1	Heated oxygen sensor heater current (after engine is warmed up)	0.4 to 1.0 A (at idle and battery voltage 11 to 14 V)

INSPECTION PROCEDURE

HINT:

• Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when the malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
• When DTC P0038 is detected, proceed to step 4 if the heater resistance is in the normal range.

In summary, the repair manual will have you do 1) inspect the heater resistance of heated oxygen sensor then skip to 4) check harness and connector (heated oxygen sensor - ECM and EFI M relay).

In step 1, if the resistances are checked and were not within specs, then replace the sensor. If the resistances are in spec, ensure the sensor is reconnected and proceed to step 4.

In step 4, it has you run various checks to ensure the integrity of the harness and connector. If a problem is found with connectors or the harness, they should be repaired or replaced. If both harness and connectors are found to be good, then the ECM should be replaced.

I have attached the full diagnostic troubleshooting steps plus the one for P0138, which has the wiring diagram.

Hope this helps.

 

if that reading is with no draw, definitely, or it might just need a charge depending on age

 

Universal obd2 tool can probably only read engine related codes. So you don't know about codes related to VSC or ABS. Best would be a Techstream and a cheap way to get it is Mini-VCI but you would need a laptop with it.

 

Clearly bad then. You might just try to charge it but probably you just need a new 12V battery.

 

the water usually comes in from the rain gutter, through cracks under the plastic molding

 

and sometimes the hatch hinges or gasket, just keep your eye on it when it rains. it won't hurt the battery, but the car can rust out. make sure the drains are clear