[emh]

P1131 - Insufficient Switching Oxygen Sensor Bank 1 Sensor 1 Sensor / Lean.

Anyone know what to do with this one? Obviously, an O2 sensor.... do I replace the sensor?

 

[jw89sho]

Yes

 

[sheila]

Upstream sensor firewall side with green elec. conn.

 

[emh]

I've done some searching on the forums.. but have found numerous instances where replacing the O2 sensor did absolutely nothing for the problem. "Fine for ~75 miles, then it came back on with the same code."

So do I replace it and just.. hold my breath and hope it works?

 

[84FordMan]

STOP!! Do NOT replace the oxygen sensor! 90% of oxygen sensor failures occur when the 24V heating element burns out, in which it has a set of codes indicating that the heater circuit has malfunctioned. The other 10% is the sensor becomes so damaged/clogged it no longer reports, in which it reports a No Activity code.

Insufficient switching means it is reporting to the ECU, however, it is staying to one side of the .450mv range and there is an underlying cause for that. If there were a vacuum leak prior to the intake manifold, but after the MAF, then both upstream oxygen sensors would be stuck on one side of the .450mv range and that would meet the qualifications for a System Too Lean code. My opinion is there is a vacuum leak, but a tiny one on the rear cylinder head, could be a pinched exhaust manifold gasket or a crack in the exhaust manifold. The EGR is also serviced off that bank so the EGR tube may be pitted/cracked, etc.

 

[BlackOmega]

84 Ford Man, Couldn't it be that vacuum boot that goes to the back of the intake that has 2 hard plastic vacuum lines running to it? I put plugs in a customers Sable, and when I was putting it back together that particular boot was swollen from oil. It wouldn't seal and kept throwing a CEL.

 

[jw89sho]

Insufficient switching means it is reporting to the ECU, however, it is staying to one side of the .450mv range and there is an underlying cause for that. If there were a vacuum leak prior to the intake manifold, but after the MAF, then both upstream oxygen sensors would be stuck on one side of the .450mv range and that would meet the qualifications for a System Too Lean code. My opinion is there is a vacuum leak, but a tiny one on the rear cylinder head, could be a pinched exhaust manifold gasket or a crack in the exhaust manifold. The EGR is also serviced off that bank so the EGR tube may be pitted/cracked, etc.

If both banks are affected by a vacuum leak, you get 0171 and 0174 codes.
If only one bank is affected, you get a code for that bank, but not both.

Insufficient switching, in my experience, indicates a lazy sensor that is in need of replacement.

Usual recommended service interval is 60-80k miles

 

[sheila]

^+1

 

[84FordMan]

If both banks are affected by a vacuum leak, you get 0171 and 0174 codes.
If only one bank is affected, you get a code for that bank, but not both.

Insufficient switching, in my experience, indicates a lazy sensor that is in need of replacement.

Usual recommended service interval is 60-80k miles

From the diagnostic table:

1. Install scan tool, bring vehicle to normal operating temperature, run KOER test. Does test indicate DTC P1133 test failed? If yes, go to Step 2, if no, go to diagnostic aids.

2. Did scan tool also indicate DTC P1153 test failed? If yes, go to step 7, if no go to step 3.

3. Inspect exhaust system for leaks, repair once found. An exhaust leak 6 to 12 inches away from HO2S can cause DTC P1133 to set. Did you isolate exhaust leak? If yes, go to step 1, if no go to step 4.

4. Visually inspect the following items, ensure that the HO2S is securely installed. Check for corrosion on the terminals. Check the terminal tension at the HO2S and at the PCM. Check for damaged wiring. Did you find a condition in any of the above items? If yes go to step 8, if no go to step 5.

5. Disconnect Bank 1 HO2S1, jumper the HO2S low (PCM side) signal circuit to a ground. Monitor the Bank 1 HO2S 1 voltage using the scan tool.Is the HO2S voltage below the specified range (350mv to 550mv)? If yes go to step 6, if no go to step 9.

6. Jumper the Bank 1 HO2S 1 high and low (PCM side) signal circuits to a ground. Monitor the Bank 1 HO2S 1 voltage using the scan tool. Is the HO2S voltage below the specified value (200mv)? If yes go to step 11, if no, go to step 10.

7. Important: Before replacing a sensor, determine and correct the cause of the contamination. Check for the following conditions: Fuel contamination, use of improper RTV sealant, engine oil/coolant consumption. Replace the affected Heated Oxygen sensor. Is the action complete? If yes go to step 12.

8. Repair the condition as necessary. Is the action complete? If yes go to step 12.

9. Repair the open Bank 1 HO2S 1 low signal circuit or grounded Bank 1 HO2S 1 high signal circuit. Is the action complete? If yes go to step 12.

10. Repair the open Bank 1 HO2S 1 high signal circuit or faulty PCM connections. Is the action complete? If yes go to step 12.

11. Replace the Bank 1 HO2S 1. Refer to Heated Oxygen Sensor (HO2S) Replacement. Is the action complete? If yes go to step 12.

12. Install scan tool, bring vehicle to normal operating temperature, run KOER test. Does the scan tool indicate that this test ran and passed? If yes, go to step 13.

13. Have yourself a beer for a job well done.

 

[sheila]

^ Cheers!

 

[emh]

Wow. Thank you so much for the suggestions. I'll get to work on it.

 

[emh]

I have to use my car tomorrow. It's still showing the code P1131.
What do I risk in driving the car "as is".
I don't risk causing any damage, do I?

 

[84FordMan]

No damage can come of it.