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P1197

Oxygen Sensor Heater Circuit Bank 2 Sensor 1 Electrical Malfunction.

  • Volkswagen
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
1
AreaFuel and air metering
97
FaultThe specific fault in that area

What it means

On Volkswagen, P1197 means the engine control unit has found an electrical fault in the heater circuit of the Bank 2 Sensor 1 oxygen sensor, the sensor upstream of the catalyst on the second cylinder bank. The control unit switches the heater and monitors its current and voltage, and it set the code because the readings did not match what it expected. Which cylinder bank is Bank 2 and the exact fault detection method depend on the engine.

Symptoms

  • Engine management warning light on
  • Poor or erratic fuel economy
  • Slightly rough running or hesitation, especially after a cold start
  • Longer time in open-loop fuelling after starting
  • Possible emissions test failure
  • Other oxygen sensor or fuel trim codes stored alongside

Possible causes

  • Failed heater element inside the Bank 2 Sensor 1 oxygen sensorlikely
  • Damaged, chafed or heat-affected wiring to the sensor heaterlikely
  • Corroded, loose or contaminated sensor connector or pinslikely
  • Blown fuse or poor power supply to the heater circuitpossible
  • Poor earth or open/short circuit in the heater control line between sensor and control unitpossible
  • Fault in the heater driver within the engine control unitrare

How to diagnose

  1. Read all stored codes and freeze frame data, noting engine temperature and whether other oxygen sensor codes are present
  2. Confirm which sensor is Bank 2 Sensor 1 for this engine using the manufacturer's data
  3. Inspect the sensor wiring and connector for chafing, melting, oil contamination, corrosion and damage near the exhaust
  4. Check the relevant fuse and the heater supply voltage at the sensor connector with the ignition on
  5. Measure the heater element resistance across the sensor heater pins and compare with the specification for that sensor
  6. Check the heater control wire for continuity, short to earth and short to supply between the sensor connector and the control unit
  7. Use live data or an actuator test to see whether the heater is being driven and whether the sensor warms up
  8. Clear the code and road test to see if it returns, which helps spot an intermittent wiring or connector fault

How to fix

  • Replace the Bank 2 Sensor 1 oxygen sensor if the heater element is open circuit or out of specification
  • Repair or replace damaged wiring, ensuring it is routed clear of hot exhaust parts and secured
  • Clean or replace corroded connector terminals or the connector housing
  • Replace the blown fuse after finding and correcting the cause of the overload
  • Restore any poor earth or power supply connection found in the heater circuit
  • Have the control unit tested and repaired or replaced only after all wiring and sensor checks have passed

Can I keep driving?

Low severity

The car can normally be driven while you arrange a repair, as this fault does not usually cause immediate damage. Fuel economy and emissions may suffer, and a prolonged fault can affect fuelling control, so do not leave it for long.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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