P0142 code meaning
O2 Sensor Circuit Bank 1 Sensor 3
Powertrain system Generic code P01xx codes Check engine light
What P0142 means
Sensor 3 is a third oxygen sensor on bank 1, behind a second converter or converter brick. It only exists on some vehicles – documented for Jaguar Land Rover's 3.0 V6 supercharged (2013–2016, where sensor 2 is 'mid-cat' and sensor 3 'post-cat') and Ford systems that monitor part of the converter volume. P0142 is the general circuit code of this sensor. Jaguar Land Rover lists it with P0143, P0144 and P0147 for the post-cat sensor and names software (fixed by reconfiguring the engine module) and water-induced thermal shock as causes. No published thresholds exist for sensor 3; the logic follows the sensor 2 checks (P0136). When it fails, the control module stops the downstream trim and cannot evaluate the converter; there is no limp mode.
P0142 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.2 to 1 hours
- Clears after repairAfter a drive cycle
Symptoms of P0142
- Check engine light on (usually after two drive cycles)
- Catalyst monitor readiness not set
- Usually no noticeable change in driving
Common causes of P0142
- Most likelySensor 3 faulty (thermal shock, ageing)
- PossibleWiring or connector under the car damaged or corroded
- PossibleEngine module software (Jaguar Land Rover)
- Less likelyExhaust leak ahead of sensor 3
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor bank1 sensor3Oxygen sensor wiringCatalytic converter
What each part of P0142 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. |
| 42 | The exact fault in that area. |
What to do next
- Note P0142 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 P0142
What does P0142 mean?
P0142 means "O2 Sensor Circuit Bank 1 Sensor 3". Sensor 3 is a third oxygen sensor on bank 1, behind a second converter or converter brick. It is a generic code, so it means the same on every make.
Is it safe to drive with P0142?
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 P0142 fail an emissions test?
Yes, it can. P0142 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 P0142 to fix?
Difficulty: easy. A typical repair takes 0.2 to 1 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0142 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.