P1116–P1122 O2 Sensor Heater Circuit, Bank 1 Sensor 1 - Open Circuit

Which code is which

Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.

The definition

P1116: O2 Sensor Heater Circuit, Bank 1 Sensor 1 - Open Circuit.

P1116 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:

1. Check the connector is fully seated and the locking tab is engaged. A half-seated plug is the single most common cause of an open circuit.
2. Back-probe the pins and check continuity from the part back to the module connector.
3. Inspect for a pushed-back or corroded terminal - the wire looks fine but the pin has backed out of the housing.

What actually causes this on a VAG

The front lambda sensor on bank 1 has a heater element that brings it up to working temperature quickly after a cold start. This code means the ECU cannot see a complete circuit through that heater at all - a break somewhere, or a burnt-out element. Typical effects are an engine light, worse cold-running economy and a failed emissions test, while the car otherwise drives normally once it is warm.

Most likely causes, in order

1. Blown fuse or lost supply feeding the heater. On many of these cars the sensor heaters are fed through a shared fuse or relay. Check this first, especially if more than one sensor is reporting a heater fault at the same time - a single fuse explains several codes at once and no amount of sensor replacement will cure it.
2. Broken wire or unlatched connector. Look at the plug first: unclicked, corroded, or with a pin backed out of the housing. Then follow the wires, paying attention to where they enter the sensor body and the plug, since a conductor often breaks inside intact-looking insulation at those flex points.
3. Heater element burnt out inside the sensor. These elements fail with age and are also killed by thermal shock - driving through standing water, or a coolant or oil leak dripping onto a hot sensor. With the sensor unplugged, no continuity at all between the two heater pins confirms it. A healthy heater reads only a few ohms, so a low reading is what you want to see, not a fault.
4. Corroded pins giving an intermittent open. If the fault comes and goes with weather or rough roads, suspect pin corrosion rather than a clean break. Wiggle-testing the plug and lead while watching the live fault status will usually reproduce it.

Worth knowing: If your scan shows heater faults on two or more lambda sensors at once, stop looking at the sensors. Two heaters failing at the same moment is rare - that pattern almost always means a shared fuse, relay, supply wire or earth, and that is a far cheaper thing to put right than a set of sensors.

Common questions

What does P1116 mean?

P1116 means O2 Sensor Heater Circuit, Bank 1 Sensor 1 - Open Circuit. The circuit is broken somewhere - a cut wire, a corroded pin or an unplugged connector means the signal never arrives.

Can I drive with P1116?

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.

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