2000 Dodge Durango is generating Check engine codes PO135 (front oxygen sensor bank 1) & PO155 (front oxygen sensor bank 2).

Hello
Lets look at these codes and what they imply is a problem.
P0135 - O2 Sensor Heater Circuit Malfunction Bank 1 Sensor
P0155 - O2 Sensor Heater Circuit Malfunction Bank 2 Sensor
The O2 sensors in this system have tiny wire filament heater in them, this allows the O2 to reach operating temperature very fast, if you turn the key on and wait a few seconds on a cold engine you will feel the sensors get hot very quickly, hot enough to burn your fingers. Here are the reason's that cause the codes to set for the heater circuits of the sensors.

Heated Oxygen Sensor (H2OS) Banks 1 and 2 Sensor #1 circuit open shorted to ground.
- Heated Oxygen Sensor (H2OS) Banks 1 and 2 Sensor #1 circuit poor electrical connection.
- Faulty Heated Oxygen Sensor (H2OS) Banks 1 and 2 Sensor #1 circuit (both of them, no not likely)
- Heated Oxygen Sensor (H2OS) Banks 1 and 2 Sensor #1 circuit fuse or fuses blown/open. (Very likely)
- Faulty Engine Control Module (ECM) (very unlikely)

Hello,

Find the meaning/interpretations of the codes below:

PO135 (front oxygen sensor bank 1)

What does that mean?

This involves the front oxygen sensor on Bank 1. This code indicates that the heated oxygen sensor reading is too high. In the case of Ford vehicles, that indicates the voltage at the sensor is over 1.5 volts. Other vehicles may be similar.

Bank 1: Quite simply, Bank 1 refers to the side of the engine that has the #1 cylinder. Bank 2 is the opposite side of the engine.

It's not correct to simply state that driver's side is always cylinder #1 or vice versa. Even on cars with a tranverse mounted engine, bank #1 is referring to downstream from the side of the engine with cylinder #1.

Symptoms

You will likely not notice any drivability problems.

Causes

A code P0132 may mean that one or more of the following has happened:

* The oxygen sensor heater circuit is shorted out
* The wiring to the sensor is broken / frayed (less likely)

Possible Solutions

The simplest thing to do is to reset the code and see if it comes back.

If the code comes back, the problem is more than likely the front Bank 1 oxygen sensor. You will likely wind up replacing it but you should also consider these possible solutions:

* Check for wiring problems (shorted, frayed wires)
* Check the voltage of the oxygen sensor

PO155 (front oxygen sensor bank 2)

02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

What does that mean?

This code refers to the front oxygen sensor on Bank 2. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0155.

Potential Symptoms

You will likely notice poor fuel economy.....

Causes

A code 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

Possible Solutions

* 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).

I hope you understand why those codes where generated on your 2000 Dodge Durango....

Let me know if you need further assistance.

Regards.