P0157 OBD-II Trouble Code: 02 Sensor Circuit Low Voltage (Bank 2 Sensor 2)

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0157 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0157 code

P0157 is a diagnostic trouble code (DTC) for "02 Sensor Circuit Low Voltage (Bank 2 Sensor 2)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $69.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$69.99$20.00
Toyota$69.99$20.00
BMW$69.99$20.00
SCHEDULE P0157 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P0157 code definition

Oxygen Sensor Circuit Low Voltage (Bank 2 Sensor 2)

What the P0157 code means

The oxygen sensor that trouble code P0157 refers to, is located in the rear of the exhaust and behind the catalytic converter. It’s main function is to regulate the amount of oxygen that comes from the catalytic converter. A lean mixture of oxygen and gas means that there is too much oxygen in the exhaust. A rich mixture of oxygen and gas means that there is not enough oxygen in the exhaust.

Neither a lean mixture or rich mixture is good for the catalytic converter and both can cause premature failure of the catalytic converter. The oxygen sensor switches back and forth from low voltage (lean) to high voltage (rich). When this code is stored by the power control module (PCM), it means that the oxygen sensor has remained at a low voltage for too long.

What causes the P0157 code?

  • Faulty oxygen sensor (bank 2 sensor 2)
  • Insufficient fuel pressure
  • False reading of the oxygen sensor as a result of holes in the exhaust
  • Corrosion of the rear oxygen sensor’s connector
  • Fuel or coolant leaks on the rear oxygen sensor
  • Broken, shorted or exposed wires
  • Malfunction of the engine coolant temperature sensor
  • Defective power control module (PCM)
  • Update required for power control module (PCM)

What are the symptoms of the P0157 code?

  • Increase in fuel consumption
  • Check Engine Light is on
  • Engine runs rough or idles poorly
  • In some rare cases, there will be no symptoms noticed by the driver.

How does a mechanic diagnose the P0157 code?

  • Collects trouble code and views freeze frame data from the OBD-II scanner.

  • Also uses scan tool to monitor oxygen sensor voltage to see if it is switching properly.

  • If an engine coolant temperature sensor trouble code is present as well, view its live data to see if it is working properly.

  • Checks fuel pressure with fuel pressure gauge. Proper fuel pressure should be at 40 psi.

  • Inspects the exhaust for air leaks in the manifold and pipes.

  • Inspects the rear oxygen sensor wires for shorts, breaks or exposure.

  • The computer may need to be updated at the dealer.

  • Advance diagnosis may also be necessary to determine if there is a problem with the Primary Control Module (PCM).

Common mistakes when diagnosing the P0157 code

  • Replacing the oxygen sensor without confirming it is bad
  • Not inspecting the condition of the oxygen sensor wires
  • Not being able to inspect the condition of the exhaust

How serious is the P0157 code?

The P0157 trouble code is considered moderately serious. It can cause drivability issues and has the potential of causing the car to stall out. If not addressed, damage to the catalytic converter can be done over time, which will be expensive to fix. It is recommended to have this problem addressed as soon as possible.

What repairs can fix the P0157 code?

  • Replacing the rear oxygen sensor
  • Repairing of broken circuitry or shorted wires going to the oxygen sensor
  • If the fuel pressure is abnormal, repairing the cause of the abnormality
  • Repairing the engine coolant temperature sensor if it is faulty
  • Replacing the power control module (PCM) or having it updated, if necessary

Additional comments for consideration regarding the P0157 code

If the oxygen sensor has ceased up in the exhaust pipe, which is common, specialty tools will be required. An oxygen sensor set will make it easier to reach an oxygen sensor that is positioned awkwardly, and a propane torch is used as a heating element to assist in the removal.

Need help with a P0157 code?

YourMechanic offers certified mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

P0157
Check Engine Light
trouble codes

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0157 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

4,240

Rating Summary
3,884
174
45
26
111
3,884
174
45
26
111
Bret

Bret

39 years of experience
52 reviews
Bret
39 years of experience
As like before....Bret was prompt n very efficient
1999 AUDI A6 QUATTRO - CHECK ENGINE LIGHT IS ON - MARTINEZ, CALIFORNIA
Harold

Harold

30 years of experience
20 reviews
Harold
30 years of experience
Came as expected, did not rush the job, had no leftover parts, and informative
2008 CHEVROLET IMPALA - CHECK ENGINE LIGHT IS ON - ORANGE PARK, FLORIDA
Richard

Richard

8 years of experience
246 reviews
Richard
8 years of experience
Always very professional and polite. Shows up on time and finds the problem and tries to get your vehicle fixed as soon as possible. If you don't need something done he will let you know so you are not paying for stuff you don't need.
2002 GMC ENVOY - CHECK ENGINE LIGHT IS ON - HERMITAGE, TENNESSEE
Patrick

Patrick

30 years of experience
865 reviews
Patrick
30 years of experience
Patrick is an outstanding mechanic! He is always professional and on time. I consider him My Mechanic from Your Mechanic.
1996 CHEVROLET CAMARO - CHECK ENGINE LIGHT IS ON - AUSTIN, TEXAS

More related articles

How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
Auto Safety Tips
Driving is more than a way to get from point A to point B. Owning and driving a car can also be a highly enjoyable experience. Whether a person is driving...

Related questions

Q: Trouble running when the engine warms up, dash lights on - 2007 Subaru B9 Tribeca

The P0137/P0157 codes indicate the "rear" (behind the catalytic converters) oxygen sensors are not functioning properly. In turn, they are signaling (incorrectly) for more fuel, which is causing the P0172/P0175 over-rich codes. This is clogging your converters, as well as...

Q: Is it the part or a deeper problem when the camshaft position sensor error displays after replacement

As a technician, anytime two sensors fail at once, I suspect there is something that both these sensors have in common. This common item is the likely point of failure. It is unlikely that two sensors would fail at the...

Q: Malfunction Transmission light appeared on dashboard

Automatic transmissions can be tricky. Luckily, as odd as it seems, the fact your vehicle is setting a warning light is a good thing. This allow you to run a diagnostic scan for trouble codes, and will help narrow down...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com