Suzuki SX4 P0057: Meaning + Causes

P0057 Suzuki SX4

P0057 is a generic trouble code, which means that it has the same definition for the Suzuki SX4 as it would any other vehicle.

It indicates that the O2 sensor at bank 2 sensor 2 has a heated element that is sending a signal back to the ECM that is below its normal operating range.

The most common fix for P0057 is a new H02 sensor or repairing the wiring harness.

P0057 Definition: Heated O2 Sensor -Circuit Low (Bank 2, Sensor 2)

Here’s the definition of P0057 for the Suzuki SX4. It has three main components:

1. Heated O2 Sensor

The heated oxygen sensor is responsible for measuring the oxygen content of the exhaust. The PCM uses this data to adjust the air-fuel mixture to the optimal 14.7 parts air to 1 part fuel, although bank 2 sensor 2 mostly just checks emissions readings.

Your SX4’s PCM can turn on the heated element to raise the temperature of the Oxygen sensor to enter closed loop operation quicker than it otherwise could.

2. Circuit Low

“Circuit Low” Indicates that PCM is having an issue detecting a response from the heated oxygen sensor circuit or that the signal coming from it is below the threshold for regular operation.

The service engine soon light will come on, and P0057 is stored in the PCM’s memory.

Bank Two, Sensor Two (B2S2)

Bank two is the part of your Suzuki SX4’s engine with the second cylinder. It is almost always the cylinder head that is facing a little more forward than the other in relation to the engine accessories.

Sensor 2

Sensor two is easy to identify. Start from bank two and follow the exhaust. It’s the second one in line. The HO2 sensor should be right after the catalytic converter.

P0057 Symptoms: Suzuki SX4

There aren’t any noticeable symptoms associated with P0057, as long as it appears by itself. The check engine light will likely be the only symptom your SX4 experiences.

Once the oxygen sensor heats up enough from the exhaust, the need for a heater disappears, and everything should be normal (other than the check engine light not turning off).

Suzuki SX4: P0057 Causes & Diagnosis

P0057 Diagnosis

Here are the most common causes of P0057 and a decent order of operations for diagnosing it.

1. Check the Wiring on Bank 2 Sensor 2

Since the PCM is not getting a response from the H02 sensor, check its wiring harness for damage.

First, inspect the harness going to your SX4’s B2S2 H02 sensor. Pay extra close attention to where the harness may have come into contact or rubbed something. Look for burnt or damaged wiring. Bad wiring is a VERY COMMON cause for P0057.

Take at where it plugs in and see if there has been any damage to the pins. If they appear corroded, get some electrical contact cleaner and clean them up. If they are damaged, you will need to repin or replace your wiring harness.

2a. Test the Oxygen Sensor – Swap Test

This can not be done if you have P0057 and P0037

Since your SX4 has two banks, you can do the “swap test.” This involves clearing the codes and seeing if the code “jumps” to bank 2 sensor 2.

Here’s how the swap test is done:

  • Clear the DTC codes with your scanner.
  • Swap the Bank 1 Sensor 2 O2 sensor with the Bank 2 Sensor 2. It should be right after the catalytic converter.
  • Run your SX4’s engine until the check engine light comes back on.
  • If the code changes to P0037, that’s proof enough you need to replace the oxygen sensor you swapped.
  • If the code remains P0057, you’ll need to continue pursuing your diagnosis, knowing that both O2 sensors are working fine.

2b. Test the Oxygen Sensor – Capture the Short/Long Term Fuel Trim Values

If you happen to have access to a scan tool, you can use it to capture your SX4’s short and long-term fuel trim values. You’ll need to make sure that the engine is warmed up before you do this.

Doing this will help you determine if the HO2 sensor is operating within spec without looking under the hood. Compare the values that you captured with your tool with the values Suzuki specifies.

While this isn’t a skill most DIY mechanics have, the concept is simple, and you can learn enough to use fuel trim to your advantage by watching this 11-minute video (it’s worth it). 

3. Not Likely – Bad ECM

It’s not very likely that a bad ECM caused P0057, but it can happen. We recommend taking it to a shop before attempting to replace it.


P0057 in your Suzuki SX4 is most likely caused by a bad Oxygen sensor, or the wiring going to/from it. The swap test is a quick and easy way to verify if the sensor or wiring harness is causing the problem.

Good luck!