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P1153

HO2S Insufficient Switching.

  • Saturn
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
1
AreaFuel and air metering
53
FaultThe specific fault in that area

What it means

On a Saturn, P1153 means the heated oxygen sensor (HO2S) is not switching between rich and lean as often or as quickly as the engine control module expects. The module monitors the sensor's voltage while the engine is warm and in closed loop fuel control. When the signal stays lazy, flat or biased, it sets the code. The sensor involved (bank and position) and the exact test conditions depend on the model and engine, so confirm these in the service information for the vehicle.

Symptoms

  • Malfunction indicator lamp on
  • Slightly higher fuel consumption
  • Rough or unstable idle in some cases
  • Hesitation or poor driveability
  • Possible failed emissions test

Possible causes

  • Ageing or contaminated oxygen sensor with a slow or lazy responselikely
  • Damaged wiring, poor connector contact or corrosion in the sensor circuitpossible
  • Exhaust leak near the sensor letting in false airpossible
  • Vacuum leak or unmetered air causing a persistently lean mixturepossible
  • Fuel delivery or injector fault causing a fixed rich or lean mixturepossible
  • Sensor contamination from coolant, oil or siliconerare
  • Fault in the engine control modulerare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data, such as engine temperature, load and fuel trims
  2. Check for other fuel trim, misfire or air flow related codes that might point to the root cause
  3. Visually inspect the sensor wiring and connector for chafing, heat damage, water ingress and corrosion
  4. Check the exhaust for leaks upstream of and around the sensor
  5. Inspect for vacuum leaks, split intake hoses and a faulty air flow or pressure sensor reading
  6. View live sensor voltage with the engine warm and in closed loop: a healthy sensor should swing quickly between low and high voltage
  7. Check short and long term fuel trims at idle and at cruise to see whether the mixture is biased
  8. Test fuel pressure and injector operation if the trims show a persistent fault

How to fix

  • Repair or replace damaged wiring or connectors in the sensor circuit
  • Replace the oxygen sensor if it is slow, flat or contaminated, using the correct part for the engine
  • Repair any exhaust leak near the sensor
  • Fix vacuum or intake air leaks and replace any faulty air flow or pressure sensor
  • Correct fuel supply or injector faults found during testing, and trace and cure any source of contamination
  • Clear the code and road test to confirm it does not return

Can I keep driving?

Low severity

The car can normally be driven, but book it in soon as fuel economy and emissions may suffer. If the engine runs badly or other warning lights appear, have it checked sooner.

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

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