P1115–P1121 O2 Sensor Heater Circuit, Bank 1 Sensor 1 - Short to Ground
A wire in this circuit is touching the car's metal body, so current escapes to earth instead of reaching the part.
Can you drive it? The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.
Which code is which
Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.
| Code | Definition | Severity |
|---|---|---|
P1115 | O2 Sensor Heater Circuit, Bank 1 Sensor 1 - Short to Ground | Investigate soon |
P1117 | O2 Sensor Heater Circuit, Bank 1 Sensor 2 - Short to Ground | Investigate soon |
P1119 | O2 Sensor Heater Circuit, Bank 2 Sensor 1 - Short to Ground | Investigate soon |
P1121 | O2 Sensor Heater Circuit, Bank 2 Sensor 2 - Short to Ground | Investigate soon |
The definition
P1115: O2 Sensor Heater Circuit, Bank 1 Sensor 1 - Short to Ground.
P1115 is a manufacturer-specific powertrain code (the engine or gearbox). Its meaning is set by the carmaker rather than by the SAE standard, so a generic OBD-II reader will often show it as an unknown code or misread it.
What to check first
Cheapest and fastest checks first:
- Unplug the connector at the part and measure resistance from each signal pin to a good earth. A healthy circuit reads open, not a few ohms.
- Follow the loom for chafe points - where it crosses a bracket, passes an edge, or flexes near a hinge or the engine mounts.
- Look for water or corrosion in the connector. A wet plug shorts pins to each other and to the body.
What actually causes this on a VAG
Your front lambda sensor - the one before the catalyst on bank 1 - has a built-in heater so it reaches operating temperature within seconds of a cold start rather than waiting for the exhaust to warm it. This code says the ECU has detected the heater circuit shorted to earth. The measuring element may well be working perfectly; it is the heating side that is at fault. The ECU normally shuts that output down once it sees a short, so the sensor stays cold and the car runs on a fixed fuelling map for longer after each cold start, hurting economy and emissions until it is fixed.
Most likely causes, in order
- Chafed or heat-damaged sensor wiring. The lambda loom runs past the exhaust, turbo and gearbox and is regularly pinched, melted or trapped, particularly after clutch, turbo or exhaust work. Trace every wire from the sensor to the plug - four on an older narrowband sensor, five or six on the wideband sensors used on most modern VAG petrol engines - looking for melted insulation, flattened sections, or a lead pulled tight over a bracket.
- Contaminated or corroded sensor connector. The plug commonly sits low down near the bulkhead or gearbox where it collects water and salt, and oil or coolant can also wick up inside the wires from a leak further forward. Unplug it, look for corrosion or wetness on the pins and inside the housing, and dry and clean it before drawing any conclusion.
- Heater failed short inside the sensor. With the sensor unplugged, check between a heater pin and the sensor body or a chassis earth - continuity there means the element has broken down internally and the sensor is finished. One thing not to misread: a heater is only a few ohms end to end, so a low reading across the two heater pins is normal and healthy, not a short.
- Poor quality or wrongly specified replacement sensor. Universal sensors that have to be spliced in, and cheap pattern parts fitted to the wrong engine code, are a frequent source of repeat heater faults. If a sensor was fitted recently, check it is the correct one for your exact engine code and that any splices are sound and properly sealed.
Worth knowing: Do this before ordering anything: unplug the sensor, clear the fault, then key-cycle and let the car run. If the stored code changes to an open-circuit heater fault, the short was inside the sensor and a new sensor fixes it. If the short-to-earth code comes straight back with nothing plugged in, the fault is in the harness between the plug and the ECU - and a new sensor would have made no difference at all.
Reading the code is the easy part
A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.
VAGPULSE reads every module in a VW, Audi, Skoda or SEAT — not just the engine — shows the live measuring blocks behind this fault, gives you the freeze-frame conditions it was logged under, and clears it once you have fixed it. It also does what a generic OBD reader cannot on a VAG: service resets, coding, adaptations, and Stage 1–3 flashing with your original file saved first.
$249 once. No subscription, unlimited cars. Windows 10/11.
See VAGPULSE — $249 Look up another codeSoftware downloads instantly · cable ships September 30 · cable guarantee — refund if it won't connect
Prefer to work on your phone? The VAGPULSE Android app is a free download and its demo mode runs against a sample car with no hardware at all, so you can see exactly what it reads before spending anything. Reading your car with it needs the VAGPULSE cable, which comes with the licence.
Common questions
What does P1115 mean?
P1115 means O2 Sensor Heater Circuit, Bank 1 Sensor 1 - Short to Ground. A wire in this circuit is touching the car's metal body, so current escapes to earth instead of reaching the part.
Can I drive with P1115?
The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.