P1156 — 9 documented meanings by make
Documented by: AUDI, BMW, CHEVROLET (USA), CITROEN, FORD, MAZDA, PEUGEOT, SEAT, SKODA, TOYOTA, VOLKSWAGEN — the meaning can differ between manufacturers
P1156 does not mean the same thing on every car — manufacturers reuse the number for different faults. 11 makes document it: Audi, BMW, Chevrolet (USA), Citroen, Ford, Mazda, Peugeot, SEAT, Skoda, Toyota, Volkswagen. Find your make below.
| Make | Documented meaning | Points at |
|---|---|---|
| Audi | Inlet manifold pressure sender, G71, open or short circuit to ground | short to ground |
| SEAT | Inlet manifold pressure sender, G71, open or short circuit to ground | short to ground |
| Skoda | Inlet manifold pressure sender, G71, open or short circuit to ground | short to ground |
| Volkswagen | Inlet manifold pressure sender, G71, open or short circuit to ground | short to ground |
| BMW | Oxygen sensor heater circuit, low voltage, bank 2 sensor 2 | oxygen sensor · signal too low |
| Chevrolet (USA) | Heated oxygen sensor rich mean, bank 2 sensor 1 | oxygen sensor |
| Citroen | Fuel select switch | |
| Citroen | Throttle valve position, track 2 | |
| Ford | Fuel select switch circuit | |
| Mazda | Fuel select switch did not switch | |
| Peugeot | Throttle valve position, track nr. 2 | |
| Toyota | Air fuel ratio sensor heater circuit, bank 2 sensor 1 |
P1156 on Audi, SEAT, Skoda, Volkswagen
On Audi, SEAT, Skoda, Volkswagen vehicles P1156 is documented as: Inlet manifold pressure sender, G71, open or short circuit to ground. P1156 is stored when the ECU sees short to ground on the circuit named in the code. That describes how the circuit is behaving, not which part has failed — the wiring, the connector and the component itself can all produce it, which is why the checks below start with the cheapest.
Usually one of: Wiring insulation chafed through where the loom passes a bracket or edge; Water or salt in a connector bridging the signal pin to the body; The component itself shorted internally; A harness pinched during earlier repair work.
Check first, cheapest first:
- Unplug the component and re-read the code — if it changes, the fault is in the component, not the wiring
- Inspect the loom where it passes metal edges, brackets and hinges
- Open the connector and check for green corrosion or moisture
- Measure resistance from the signal pin to a body ground; near-zero confirms the short
- Repair the harness section, or replace the component if it shorted internally
Related Audi, SEAT, Skoda, Volkswagen codes:
P1156 on BMW
On BMW vehicles P1156 is documented as: Oxygen sensor heater circuit, low voltage, bank 2 sensor 2. P1156 is stored when the ECU sees signal too low on oxygen sensor (bank 2, sensor 2). That describes how the circuit is behaving, not which part has failed — the wiring, the connector and the component itself can all produce it, which is why the checks below start with the cheapest.
Usually one of: High resistance in the supply or ground path, dragging the signal down; Corroded connector adding resistance the module reads as a low reading; Sensor drifted out of tolerance with age; Partial short to ground somewhere in the signal line.
Check first, cheapest first:
- Read the live value on a scanner and compare with a known-good reading
- Clean and re-seat the connector, then re-test before replacing anything
- Check the ground point for that circuit — a poor ground causes this far more often than a bad sensor
- Measure the sensor against specification with the connector back-probed
- Replace the sensor only once the wiring and ground have been ruled out
Related BMW codes:
P1156 on Chevrolet (USA)
On Chevrolet (USA) vehicles P1156 is documented as: Heated oxygen sensor rich mean, bank 2 sensor 1. P1156 points at oxygen sensor (bank 2, sensor 1). The standard definition names the system involved; which part inside it has actually failed is what the checks below establish, cheapest first.
Usually one of: Sensor aged and slow to respond; Heater element failed inside the sensor; Wiring or connector fault at the sensor; Exhaust leak near the sensor drawing in air; Engine genuinely running rich or lean.
Check first, cheapest first:
- Read the sensor's live trace — a lazy or flat signal identifies an aged sensor without removing anything
- Check for exhaust leaks upstream of the sensor
- Inspect the connector, which sits in a hot and exposed place and corrodes
- Measure the heater resistance against specification
- Replace the sensor once the exhaust and wiring are ruled out
Related Chevrolet (USA) codes:
Which one is yours
A generic OBD reader gives you the number, not which of these meanings your manufacturer assigned to it. To get to the specific one:
- Use a brand-specific scanner — VCDS for VAG, INPA or ISTA for BMW, XENTRY for Mercedes, Forscan for Ford. It shows the manufacturer's own text rather than the generic one.
- Read all stored codes together — the neighbouring ones usually point at which system is involved and narrow the list.
- Check freeze-frame data: the RPM, temperature and load at the moment it triggered indicate which system was active.
- If you have no brand scanner, tell me the make and model below and I will tell you which of these applies to your car.
Code family
P1xxx is manufacturer-specific code (VW/Audi, BMW, Mercedes, Toyota etc. have different meanings for the same code number).
Severity
Manufacturer-specific codes need a brand scanner (VCDS for VAG, INPA for BMW, STAR for Mercedes).
That is what holds for P1156 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.
Why TorqFix for your car?
Above is what the code means and why it appears. TorqFix goes further — it gives you specific procedures, torque values, wiring diagrams and pinouts for your exact engine, not generic steps for every car. Real workshop data (127,000+ diagrams, 10,000+ procedures), interpreted by AI in your language.
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Code breakdown
Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
The same code can mean different things on different makes. Match the meaning to your make before acting on it.
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