P0135 O2 Oxygen Sensor Heater Circuit Malfunction

DTC P0135 Technical Description

P0135 - O2 Sensor Heater Circuit Malfunction

What does trouble code P0135 mean?

This Diagnostic Trouble Code (DTC) is a generic transmission code, which means it applies to OBD-II equipped vehicles. Although general, specific repair steps may differ depending on the brand / model.

This code applies to the front oxygen sensor on block 1. A heated loop in the oxygen sensor reduces the time it takes to enter the closed loop.

When the O2 heater reaches operating temperature, the oxygen sensor reacts by switching according to the oxygen content of the exhaust gases surrounding it. The ECM monitors how long it takes for the oxygen sensor to initiate a switchover. If the ECM determines (based on the coolant temperature) that too much time has elapsed before the oxygen sensor starts working properly, it will set P0135.

Symptoms

The most common symptoms associated with this error code are as follows:

• Turn on the classic engine warning light (Check Engine).
• Unstable engine operation.
• Unusual increase in vehicle fuel consumption.

As you can see, these are fairly general signals that can also apply to other error codes.

Causes of the P0135 code

Each vehicle has an oxygen sensor connected to the heating circuit. The latter has the task of reducing the time required to enter the closed loop mode; while the oxygen sensor will record temperature changes affecting the oxygen that is around it. The engine control module (ECM or PCM), in turn, controls the time it takes for the oxygen sensor to measure temperature changes by relating it to the coolant temperature. To put it simply: The ECM keeps track of how long it takes the sensor to warm up before it starts sending an adequate signal. If the values ​​obtained do not match the standard values ​​expected for the vehicle model, the ECM will automatically set DTC P0135. The code will indicate that the oxygen sensor is running too long due to the fact that this device must have a minimum temperature of 399 degrees Celsius (750 degrees Fahrenheit) in order for it to produce a reliable voltage signal. The faster the oxygen sensor warms up, the faster the sensor can send an accurate signal to the ECM.

Here are the most common reasons for this error code:

• Heated oxygen sensor malfunction.
• Heated oxygen sensor malfunction, fuse short circuit.
• Malfunction of the oxygen sensor itself.
• Malfunction of the electrical connection system.
• The resistance of the O2 heating element in the sensor is too high.
• Malfunction of the ECM itself, which fixed a false value.

Possible solutions

• Repair short, open, or high resistance in the wiring harness or harness connectors.
• Replace the oxygen sensor (it is not possible to eliminate the open or short circuit inside the sensor)

Repair Tips

There are several practical solutions regarding both diagnosing and resolving DTC P0135. Here are the most common:

• Check and repair any open or shorted oxygen sensor resistance.
• Check and, if necessary, repair the wiring connected to the oxygen sensor.
• Check and eventually repair or replace the oxygen sensor itself.
• Scan for error codes with an appropriate OBD-II scanner.
• Checking the oxygen sensor data to see if the heater circuit is working.

One practical tip that can be given here is not to replace the oxygen sensor until all of the above preliminary checks have been made, in particular checking the fuse and sensor connectors. Also, be aware that water entering the heated oxygen sensor connector can cause it to burn out.

Although driving a car with this error code is possible, as it does not affect driving performance, it is still recommended to take the car to a workshop as soon as possible to have the problem resolved. In fact, eventually, also due to higher fuel consumption and the possible formation of small deposits, more serious engine problems can occur, requiring more complex and costly intervention in the workshop. Other than a visual inspection of the sensor and wiring, again, doing it yourself in your home garage is not the best option.

It is difficult to estimate the upcoming costs, since a lot depends on the results of the diagnostics carried out by the mechanic. As a rule, the cost of replacing an oxygen sensor in a workshop, depending on the model, can be from 60 to 200 euros.

Frequently Asked Questions (FAQ)

What does code P0135 mean?

Code P0135 indicates a malfunction in the oxygen sensor heater circuit (bank 1 sensor 1).

What causes the P0135 code?

There are many reasons that lead to the activation of this code, and they are associated with a malfunction of the oxygen sensor or catalytic converter.

How to fix code P0135?

It is necessary to accurately check all the parts involved and, if necessary, proceed to replace them.

Can code P0135 go away on its own?

Unfortunately no. After all, if a malfunction exists, its disappearance will only be temporary.

Can I drive with code P0135?

Driving is possible, but increased fuel consumption and reduced performance must be taken into account.

How much does it cost to fix code P0135?

On average, the cost of replacing a lambda probe in a workshop, depending on the model, can range from 60 to 200 euros.

How to Fix P0135 Engine Code in 2 Minutes [1 DIY Methods / Only $19.66]

Need more help with your p0135 code?

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