What is the p1131 and the p1151 codes mean? - 2000 Lincoln Town Car

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Mercury Check Engine Light Codes Welcome to the Mercury Check Engine Light...

Hope this helps you or future parties of intrest. P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1 P1151 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2 I would get under your stang and gently clean outside portion of o2 sensors using a scotch brite. Also if you have so dielectric grease pull electrical connections to o2 sensors clean them and add grease. These trick eliminated the o2 sensor OBD1 codes on my 1987 Ford mustang gt

Autozone and some other auto part stores will scan for free and tell you what all the codes are/mean.

you can look it up on "obdii" trouble codes web site

P1131-- Lack of HO2S-11 Switch (lean)
P1151--Lack of HO2S-12 Switch (lean)

There are at least 26 possible causes in the
Diagnostic Trouble Code Chart

That isn't going to be a driveway job,
your going to resolve

Hello,
P1131 = Lack of HO2S11 switch - sensor indicates lean, ( upstream heated oxygen sensor )
This oxygen sensor is located before the catalytic converter, ( refered to as UPSTREAM )

P1151 = Lack of HO2S21 switch - sensor indicates lean, ( could be up, or downstream heated oxygen sensor ) " Downstream ", meaning after the catalytic converter.

PO174 = System too lean, ( bank 2 ) The fuel/air mix ratio is bad.

These DCT codes are generally caused by a problem with the emissions system. The following items are a few of the most common items to trigger those codes.

1. Dirty air filter. ( very common )
2. Faulty idle air control valve. ( common )
3. MAF, ( mass air flow ), sensor. ( very common )

All 3 of the above can prevent the onboard computer from determining the proper fuel/air mix ratio.
The oxygen sensors measure to insure the fuel/air mix produces maximum power with minimal emissions.

I hope this helps you.
Feel free to contact me in the comment section if you have a question.

DTC P1131 DTC P1151 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.

Start with the simple and clean the MAF and the IAT sensor. In simple terms, the engine is running lean and is being compensated by the ECM. P1131 is bank 1 and P1151 is bank2

Good luck and keep me posted.

TSB
05-22-6
ISSUE:
Some 2001-2003 F-150, 2004 F-150 Heritage and 2001-2003 E-150/250 vehicles equipped with a 4.2L engine may exhibit the malfunction indicator lamp (MIL) on with diagnostic trouble codes (DTCs) P1131 and/or P1151 (system too lean bank 1 or 2). This condition may be due to leaking isolator bolts/port gaskets in the upper-to-lower intake manifold mounting area. This condition is sometimes intermittent and may not be apparent on a warmed-up engine.


SERVICE PROCEDURE

Perform a self test. If DTC P1131 and/or P1151 are the only codes stored in the powertrain control module (PCM) proceed to Step 2. If any additional DTCs are present, follow normal diagnostic procedures found in the PC/ED Manual.

Remove the upper intake and replace only the port gaskets (9H486) and isolator bolt assemblies (9S479). The new isolator bolt assemblies use a rubber material that is green in color, do not install the old isolator bolt assemblies with the black rubber material. Do not replace any other intake parts or gaskets.
While the upper intake manifold is removed, check the exhaust gas recirculation (EGR) orifices that are pressed into each primary port of the lower intake manifold. If any of the orifices are plugged with soot, clean and unplug them with a pick and solvent.

PART NUMBER PART NAME
1L3Z-9H486-AA Port Gasket
3F2Z-9S479-AA Isolator Bolt

Change plugs, and Mass Air Flow sensor. This should do the trick

If both, P1131 and P1151 trouble codes are set at the same time, the problem will most likely be attributed to a vacuum leak past the MAF (Mass Air Flow) sensor or something else that would likely affect BOTH banks. If the problem is only causing one code or the other, but NOT both, the problem will most likely be something that would affect one bank, like a bad O-2 sensor or a fuel injector; the most common cause of a single code either the P1131 or P1151 in my experience has been a bad Oxygen sensor.