It has a code p0155 &po155pd what is the problem?

P0155 is not telling you which part is defective, it is saying there is a problem in the system and that the triggers the fault code. In this case you have a O2 sensor whose heater is not heating. This may be the senor or the wiring to it.
P0155 OBD-II Trouble Code: 02 Sensor Heater Circuit Malfunction in cylinder Bank 2 (V6 only), Sensor 1, this is the sensor before the catalyst.

those would b your o2 sensors.front first.

You can not work on a vehicle as your doing

Your checking for generic codes only & throwing
parts at it

You get a couple possible worn or failed parts & have
a few less codes

There is no need to clear ALL Data every time you change a part

You need to STOP

You need professional scan tool software to look at ALL data & go for a road test first

You keep clearing stored data ,so now the process will take longer

You work one code & one system at a time

NO PARTS get replaced that are not tested & found to fail
a test,thus a worn out part.

You need both Factory Emission & Diagnostic Manual, as well
as Wiring Diagram Book-- BEFORE-- you can even walk to the vehicle (Helm.Com)

You have nothing to go by,no system knowledge & no trouble charts,& no wiring diagrams to start your testing

If you got no scan tool & no volt meter & no oscilloscope,
your done,vehicles have to be tested to find a problem,any
problem,resolve it & continue on.

P0155 CHEVROLET - HO2S Heater Performance Bank 2 Sensor 1

Replace the cylinder back sensor.

Hi there:

DTC P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control

The simplest thing to do is to reset the code and see if it comes back.
If the code comes back, the problem is likely going to be the result of the above causes (faulty thermostat, faulty ECT sensor, or a low coolant level).


DTC P0135 - Oxygen O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
or
DTC P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

A code P0135 and P0155 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

In order to solve just...

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)

Hopoe this helps.

code p0155 is O2 sensor heater circuit
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Code P0155, 1155, will get those code's with vacuum leaks, I have seen that many times here at my repair shop, many times customers come in, after they have done a tune-up, as you have, and same problem, check for vacuum leaks, more so on top of engine to the back, by fire wall.

CODE P0155 IS O2 HEATER FAULT MOST LIKELY CAUSE IS WIRING, GROUND CONNECTIONS ,POSSIBLE ECM .

P0155 - Heated Oxygen Sensor Heater Circuit (bank 2, sensor 1)

bank 2 sensor 1 (front, driver side) o2 sensor needs to be replaced