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DTC codes / BMW codes / P1182

P1182 · BMWO2 Sensor Bank 1 Sensor 2 Open Circuit During Coast Down Fuel Cut-off

P1182 on BMW vehicles means the engine computer detected an open circuit in the post-catalytic converter oxygen sensor on Bank 1 during a coast-down fuel cut-off phase. The sensor's signal circuit is not returning the expected voltage, so the DME cannot monitor catalyst efficiency or fine-tune fuel trim during deceleration.

SystemPowertrain
Code typeBMW specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Slightly reduced fuel economy over time as the DME defaults to a richer mixture
  • Occasional hesitation or stumble during light-throttle cruising
  • A pending P1182 that returns after clearing even when the car seems to run fine
  • Failed emissions inspection due to the oxygen sensor monitor not completing

Common causes, most likely first

  1. Broken or chafed wire in the Bank 1 Sensor 2 oxygen sensor harness, especially near the exhaust heat shield
  2. Corroded or loose connector pins at the sensor or at the DME harness junction
  3. Failed post-catalyst oxygen sensor with an internally open heating or signal circuit
  4. Blown fuse or damaged relay in the oxygen sensor heater circuit
  5. Exhaust leak upstream of the sensor allowing air to enter and skew the signal
  6. DME software or internal driver fault on the sensor signal line (rare but documented)

How to diagnose and fix it

  1. Clear the code and perform a road test with a scan tool to confirm P1182 returns during coast-down fuel cut-off
  2. Visually inspect the Bank 1 Sensor 2 harness and connector for chafing, corrosion, or heat damage
  3. Measure resistance across the sensor heater circuit and compare to BMW specifications for the installed sensor
  4. Check for battery voltage and ground at the sensor connector with the key on, engine off
  5. Perform a voltage drop test on the signal wire from the sensor to the DME while wiggling the harness
  6. Repair or replace the faulty section of harness or the sensor itself, then clear codes and verify the oxygen sensor monitor completes
  7. If the circuit tests good, check for exhaust leaks upstream of the sensor and inspect DME software version for known updates

Why P1182 often fools parts swappers

  • A post-catalyst sensor can pass a static resistance test and still set P1182 because the open circuit only appears when the harness flexes during engine movement on coast-down.
  • Technicians who replace the sensor without checking the heater circuit fuse often find the new sensor sets the same code within a few drive cycles.
  • An exhaust leak between the catalyst and the sensor can mimic an open circuit by introducing oxygen that the DME interprets as a signal fault during fuel cut-off.
  • P1182 is sometimes stored alongside fuel trim codes, but the root cause is often a damaged wire near the exhaust hanger rather than a failing sensor.
  • BMW DMEs may set P1182 intermittently if the sensor connector is not fully seated after a previous repair, so always verify the lock tab clicks.

Can I keep driving with P1182?

You can usually drive the car short distances with P1182, but avoid long trips or heavy load because the DME may run a richer mixture that can damage the catalytic converter over time. Have the circuit inspected soon, especially if the check engine light flashes or fuel economy drops noticeably.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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