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david
david, Auto Service Technician
Category: Car
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Experience:  Certified Master Technician,Certified in diesel & gasoline engines
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1999 Ford Contour: the check engine light stays on I..oxygen sensors

Resolved Question:

I have a 1999 Ford Contour the check engine light stays on I have changed the heater oxygen sensors but with no luck. The code is P1131 what is bank 1 that the print out refers to?
Submitted: 8 years ago.
Category: Car
Expert:  david replied 8 years ago.

Thank you for your question hope this helps.

DTC P1131 indicates the system is correcting RICH for an overly LEAN condition. The Heated Oxygen Sensor (HO2S) voltage is less than 0.45 volts.

This is usually due to a vacuum leak after the MAF. It can also be caused by a bad PCV valve or PCV system hose.
It can also be caused by low fuel pressure or a plugged injector.

To find a vacuum leak
With the engine running listen for any whistling also with your hand reel the vacuum lines and fittings. You can also use a card cleaner spray all the vacuum lines and fittings the engine will reeve up when you spray the leak. (Be careful carburetor cleaner is vary flammable)
Repair the leak you find.

As for the PCV valve i would recommend replacing it
low fuel pressure or a plugged injector can be fixed by running a fuel cleaned at the next fill up.

 

You wanted to know what the bank 1 refers to hear is a numbering convention

graphic
Heated Oxygen Sensor Numbering Convention

  • The first oxygen sensor in cylinder bank #1 is numbered HO2S11.
  • The second oxygen sensor in cylinder bank #1 is numbered HO2S12.
  • The first oxygen sensor in cylinder bank #2 is numbered HO2S21.
  • The second oxygen sensor in cylinder bank #2 is numbered HO2S22.
  • Cylinder bank number one is the bank that contains number one cylinder.
  • If a V-6 or V-8 vehicle only uses one downstream Heated Oxygen Sensor (HO2S) it is numbered HO2S12, even if it uses two upstream HO2S.

Hope this helps

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