P0157 code meaning
O2 Sensor Circuit Low Voltage Bank 2 Sensor 2
Powertrain system Generic code P01xx codes Check engine light
What P0157 means
The oxygen sensor after the catalytic converter on bank 2 (sensor 2) is a switching sensor (about 0.1–0.9 V) used for converter monitoring and fine mixture trim. Bank 2 exists only on V and boxer engines with a separate downstream sensor per bank. P0157 means the signal stays below the lower limit, the bank 2 counterpart of P0137. GM sets it below 50 mV (two trips), on its 3.0 V6 within 50 s in closed loop; Ford uses its pull-up resistance check and counts both open circuit and short to ground as P0157. When it fails, the control module stops the downstream trim and cannot evaluate the converter; there is no limp mode.
P0157 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0157
- Check engine light on (usually after two drive cycles)
- Catalyst monitor readiness not set
- Usually no noticeable change in driving
Common causes of P0157
- Most likelySignal wire shorted to ground or melted against the exhaust
- Most likelySensor faulty (cracked element, thermal shock from water)
- PossibleSignal circuit open (counts as low on Ford)
- PossibleExhaust leak ahead of the sensor (lean reading)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor bank2 sensor2Oxygen sensor wiringCatalytic converter
What each part of P0157 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| 57 | The exact fault in that area. |
What to do next
- Note P0157 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0157
What does P0157 mean?
P0157 means "O2 Sensor Circuit Low Voltage Bank 2 Sensor 2". The oxygen sensor after the catalytic converter on bank 2 (sensor 2) is a switching sensor (about 0.1–0.9 V) used for converter monitoring and fine mixture trim. It is a generic code, so it means the same on every make.
Is it safe to drive with P0157?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0157 fail an emissions test?
Yes, it can. P0157 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0157 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0157 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.