P1151 — O2 Sensor Heater Circuit Signal Intermittent Bank 2 Sensor 1

Diagnostic algorithm

1. Connect a full‑function scan tool. Confirm P1151 is present and note freeze frame and pending/history status. Check live heater status for Bank 2 Sensor 1 while cranking and during warm‑up.
2. Perform a visual inspection of the sensor, connector and harness from the sensor back to the engine wiring junction. Look for corrosion, melted insulation, chafe points near exhaust, or pin damage.
3. With ignition OFF, disconnect the sensor and measure heater resistance across the heater pins at the sensor. Compare to BMW spec. An open or infinite resistance indicates failed heater.
4. With ignition ON (engine OFF), backprobe the connector and verify battery voltage is present at the supply terminal and a control return is present (ground switching or PWM) from the DME. If no supply, check fuses/relays and upstream wiring.
5. With engine cold and then during warmup, monitor the control signal with a scope or multimeter set to view switching. Look for intermittent loss of supply or control switching. Wiggle the harness at suspect areas to reproduce the fault.
6. Check continuity and resistance between the sensor connector and the DME pin to rule out high resistance or intermittent open. Inspect and test all relevant grounds.
7. If wiring and connectors are good but the DME output is intermittent or stuck, verify with an independent power source and consult manufacturer procedures — avoid replacing DME as first step. Consider replacing sensor with OEM‑spec unit and retest if heater element out of spec.
8. Repair any damaged wiring, replace corrupted connectors, replace the oxygen sensor if heater is failed, clear codes and perform drive cycle to verify the fault does not return and monitors complete.
9. If fault returns after correct wiring and sensor replacement, test/replace DME driver per factory diagnostics.