How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dan Your Own Question
Dan
Dan, ASE Certified Technician
Category: Buick
Satisfied Customers: 1668
Experience:  Auto Technician
94707146
Type Your Buick Question Here...
Dan is online now
A new question is answered every 9 seconds

There. I've got a '99 Buick Regal with a non-supercharged

Customer Question

Hey, there. I've got a '99 Buick Regal with a non-supercharged 3.8 liter V6. Getting a code P01133- insufficient Switching Bank 1 Sensor 1. I replaced upstream sensor, erased code but it came back shortly thereafter. Checked wiring for any breaks/shorts at harness end, but did not find any problems. Installed another new O2 from a different manufacturer, erased code again but code came back. Checked for vac leaks, checked fuel pressure (40psi), sprayed carb cleaner around intake manifold, hoses, etc, but no change in idle. My live data on my scan tool shows a somewhat sinusoidal waveform at about 1500 rpm and up but below that things start getting messy looking.
MAF was also replaced, but to no change in problem.
Submitted: 8 months ago.
Category: Buick
Expert:  Roy Belding replied 8 months ago.

Hello, my name is ***** ***** I will be glad to assist. Please allow me a moment to gather some information.

Expert:  Roy Belding replied 8 months ago.

ok, can you tell me what the long term trims are when idling???

Roy

Expert:  Roy Belding replied 8 months ago.

Circuit Description

The PCM monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During this test period the PCM counts the number of times that the HO2S signal voltage crosses the rich to lean and lean to rich thresholds. If the PCM determines that the HO2S did not switch enough times, DTC P1133 will be set. A lean to rich switch is determined when the HO2S voltage changes from less than 300 mV to greater than 600 mV. A rich to lean switch is determined when the HO2S voltage changes from more than 600 mV to less than 300 mV.

Conditions for Running the DTC

Expert:  Roy Belding replied 8 months ago.

are you there

Customer: replied 8 months ago.
Thanks for responding, Roy. I am not by the vehicle currently but will be be tonight and can check that. Just to double check, you mean the long term FUEL trim, right? since it's a v6 engine, I imagine there will be 2 seperate LTFT's, so I'll report you both values. Just so I know, should the values remain constant or change and, if they change, should I look at the graph and write down any data? Also, does it matter whether the engine is warmed up first?
Expert:  Roy Belding replied 8 months ago.

ok, engine warm and will read in percentage.

Roy

Customer: replied 8 months ago.
Okay, I drove car to warm it up, idled motor and took readings. I did not get a steady number, but rather values ranging from a low of 1.6% to a high of 10.9% over the course of several minutes.
Expert:  Roy Belding replied 8 months ago.

1.6 is good but 10.9 means it is running lean

check the pcv valve to be sure it is not stuck open

check for vacuum leaks

check the fuel pressure as well. low pressure will make it run lean

Roy

Customer: replied 8 months ago.
Okay. I have a PCV valve on order and it should be in tomorrow. As I mentioned in my original question, I checked fuel pressure and looked for vac leaks already. Fuel pressure was 40psi at idle. Pressure went up slightly when I increased rpm to about 3k but then settled quickly back to 40psi again. Regarding vacuum leaks, I replaced some suspect hoses but code returned again. I sprayed carb cleaner on other hoses in and around intake gasket manifold area but no change in idle when I did that. I will let you know if any change when the new valve is installed.
Expert:  Roy Belding replied 8 months ago.

ok

please dont forget to rate me as it is the only way I get paid for my efforts

Roy

Expert:  Roy Belding replied 8 months ago.

I did not see one of my responses posted. it is about your fuel pressure. it is under spec. low fuel pressure will cause this lean condition. the spec is below for you to view

Roy

1999 Buick Regal V6-3.8L VIN K

Vehicle » Specifications » Pressure, Vacuum and Temperature Specifications » Fuel Pressure

Key On Engine Off48-55 psi

Expert:  Roy Belding replied 8 months ago.

please dont forget to rate me as it is the only way I get paid for my efforts

Roy

Customer: replied 8 months ago.
Ok. How do you suggest I proceed to correct the low fuel pressure problem?
Expert:  Roy Belding replied 8 months ago.

replace the fuel pump is the solution

Roy

Customer: replied 8 months ago.
Roy, please read my messages completely. You are missing out on important information if you do not. The 40 psi I mentioned was with key on engine ON. I believe that falls within spec for this car. I did not test pressure with KOEO, but can do so.
Expert:  Roy Belding replied 8 months ago.

I have read all your responses.

no where do I see any pressure within the specs that are required. I am missing nothing here at all.

Customer: replied 8 months ago.
Okay. What is the fuel pressure spec for key on engine on?
Expert:  Roy Belding replied 8 months ago.

46-52 lbs key on engine running

Customer: replied 8 months ago.
OK. You only listed the KOEO spec, so I thought you missed what I said. My apologizes, Is there a chance the fuel pressure regulator could be bad and causing the low value?
Expert:  Roy Belding replied 8 months ago.

no worries

no, the pump is not building enough pressure. the pump needs to be replaced to get the pressure up to spec. then the sufficient amount of fuel will get into the cylinders and the O2 sensor will start working again.

Roy

Expert:  Roy Belding replied 8 months ago.

please dont forget to rate me as it is the only way I get paid for my efforts

Roy

Customer: replied 8 months ago.
I understand. I ordered a new pump and it should be in tomorrow. Once I get it, I'll install it and let you know how it goes.
Expert:  Roy Belding replied 8 months ago.

ok

please dont forget to rate me as it is the only way I get paid for my efforts

Roy

Customer: replied 8 months ago.
Fuel pump was changed out today. Fuel pressure is the same @ ~40psi engine running. I erased the DTC anyway, drove car or for about 15 minutes and it came back on again.
Customer: replied 8 months ago.
Do you have any further suggestions on how to resolve this problem? So you know, I checked a few online forums and according to them, 40psi koer is normal fuel pressure for the car. 45psi is in the koeo state, which is what I'm reading as well.
Expert:  Roy Belding replied 8 months ago.

with the new pump and pcv, what are the long term trims reading now???

Customer: replied 8 months ago.
Sorry for the delay. I did not have access to the car until today. I idled engine for a good 10 minutes total. With engine cold, the LTFT was 7, went up and down and eventually settled at 11.7. I kept it idling for an additional 5 minutes and the remained steady. From what you said earlier, I guess it's still running lean
Expert:  Roy Belding replied 8 months ago.

yes, it is running lean

Roy

please dont forget to rate me as it is the only way I get paid for my efforts

Roy

Customer: replied 8 months ago.
Roy, perhaps you could refer another expert to help me on this case. We seem to be at an impasse...Thank you.
Expert:  Roy Belding replied 8 months ago.

I agree. it is always 3 days waiting for a response from you anyway.

you also never stated if you replaced the pcv as it will effect long term trims

Customer: replied 8 months ago.
Thanks, ***** ***** PCV was replaced.
Expert:  Dan replied 8 months ago.

New expert here, I can send you the repair procedures for this code from the factory service manual if you would like.

Customer: replied 8 months ago.
Hello, Dan. Do I have to pay additional for this information?
Expert:  Dan replied 8 months ago.

Yes, it will allow me to email you the info you need.

Customer: replied 8 months ago.
Can you just briefly walk me through it? Not trying to be difficult, it's just that I already paid for help and I'm still no where near a resolution here.
Expert:  Dan replied 8 months ago.

Check the intake gaskets on the manifold this is a common problem. Also replace the fuel filter.

Expert:  Dan replied 8 months ago.

Also this could be a mass air flow sensor problem. I would try to clean the MAF first then replace it.

Customer: replied 8 months ago.
Thanks for doing that, Dan.In my original post you'll notice I replaced the MAF just recently and also sprayed carb cleaner all around the intake gasket perimeter but there was no change in idle. Since I last talked to Roy, I capped off all vacuum lines (except for the fuel pressure regulator) erased codes and drove car but code still returned (I vacuum tested the regulator prior to erasing code, by the way, and it tested good). Yesterday I resprayed around the intake gasket again and also around the (capped off) vacuum ports coming off the engine (there are only 2), this time with starting fluid, but again there was no change in idle speed.I have not changed the will pick up a fuel filter tomorrow and do that.
Customer: replied 8 months ago.
In the meantime, do you think there is any live data I could view view with my scanner that might help steer us the in the right direction?
Expert:  Dan replied 8 months ago.

Look at the voltage from the front O2 sensor

Expert:  Dan replied 8 months ago.

Look at the freeze frame data as well.

Customer: replied 8 months ago.
Okay, Dan. I replaced the fuel filter today and also decided to change the thermostat as well (I did that because the temp gauge never rose much above cold, heat wasn't hot and coolant temp sensor never reported much more than ~145 degree F or so).I drove car afterwards for a good couple hours. Heat is much better, temp gauge get up to where it should be and temp sensor reports a good temp of ~190 degree F. I checked for codes at two different times during the trip. Pending code p1133, which was in the PCM prior to the aforementioned repairs, went away at 1st check but returned at 2nd check. It hasn't progressed to a full DTC as of yet, so there's no freeze frame data I can provide you with.Regarding the O2 voltages you mentioned, I wasn't sure what you specifically you wanted me to look for since the values change continuously. I did look at the voltage graph and during scan #1 the voltages looked very sinuisodial (as I believe they're supposed to look), but on scan #2 they looked much less so (if it would help to take a picture of the graph and upload it for you, I can do that).I'll continue to drive the car and report anything additional. In the meantime, would you have additional thoughts/suggestions?
Expert:  Dan replied 8 months ago.

Keep driving it until you get a code, then show me the freeze frame data. Is it running any better than before?

Expert:  Dan replied 8 months ago.

Hello again Dan here,

I am contacting you because the post has not been closed or rated.

This question is coming up on 7 days which means it will time out and close.

You have already paid to get this question answered, but you have not rated.

Let me help some more. Is there anything else I can help you with?

If I did not give you 5 star service, please let me know what I missed.

Thanks

Customer: replied 8 months ago.
OK, will do. To answer your question, the car has always run perfectly fine despite the issue with the code. We just can't get it to pass inspection as it is.
Expert:  Dan replied 8 months ago.

DTC P1133

DTC P1133: HO2S INSUFFICIENT SWITCHING SENSOR 1 (3.8L "C", "G", "H" & "W" BODIES)

NOTE: For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Circuit Description

PCM monitors Heated Oxygen Sensor (HO2S) activity for 100 seconds. PCM determines if HO2S 1 is functioning properly by counting number of HO2S 1 Lean/Rich (L/R) and Rich/Lean (R/L) switches. If PCM determines that HO2S 1 did not switch enough times, DTC 1133 is set.

Conditions for setting DTC are: PCM monitors fewer than 40 lean-to-rich and rich-to-lean switches for bank 1, sensor 1 HO2S, HO2S voltage remains between 300-600 mV and conditions are present for 2 minutes after "closed-loop" enable.

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
  2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If any DTC other than P1133 or P1134 sets, diagnose affected DTC before proceeding. If no other DTC sets, start engine and allow it to idle. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1133 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1133 FAILED THIS IGN, go to DIAGNOSTIC AIDS .
  3. Check exhaust system for leaks. Repair as necessary. After repairs, go to step 11. If no exhaust leak is found, go to next step.
  4. Visually inspect HO2S 1 for secure installation or corrosion on terminals. Check terminal tension at HO2S 1 and PCM. Check for damaged wiring. If a problem is found, go to step 8. If no problem is found, go to next step.
  5. Disconnect HO2S 1 harness connector. Connect a jumper wire between HO2S 1 harness connector ground circuit and chassis ground. Using scan tool, read HO2S 1 voltage. If voltage reading is about 0.45 volt, go to next step. If voltage reading is not about 0.45 volt, go to step 9.
  6. Connect a jumper wire between HO2S 1 harness connector signal and ground circuits, and chassis ground. If voltage reading is less than 0.3 volt, go to next step. If voltage reading is not less than 0.3 volt, go to step 10.
  7. Repair condition causing fuel, sealant, oil or coolant contamination. Replace affected HO2S. After repairs, go to step 11.
  8. Repair condition as necessary. After repairs, go to step 11.
  9. Repair open HO2S 1 ground circuit or HO2S 1 signal circuit shorted to ground. After repairs, go to step 11.
  10. Repair open HO2S 1 signal circuit or faulty PCM connections as necessary. After repairs, go to next step.
  11. Using scan tool, read and record FAILURE RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1133. If scan tool displays DTC P1133 FAILED THIS IGN, return to step 2. If scan tool does not display DTC P1133 FAILED THIS IGN, repair is complete.

Diagnostic Aids

Check HO2S 1 heater operation. If HO2S 1 heater operation is okay, replace HO2S 1.

Expert:  Dan replied 8 months ago.

Need to go through all 11 steps in order to diagnose.

Customer: replied 7 months ago.
The CEL popped on today. Scanned and got p0141- sensor heater circuit malfunction bank 1 sensor 2 (P0133 is still in pending state). I got that one a month ago and it turned out to be a blown fuse. I checked the fuse again but it was fine. I also tested the heater element & got 5 ohms, which is in spec and.tested harness plug at terminal C & D for ground and + 12Vdc, respectively, and got that. Not sure what's goin on there.Anyway, I looked at live data on 02 b1s1 today and the waveform was erratic and voltages were small. I moved the wires coming from the main harness going to the sensor and the waveform improved dramatically as did voltages. I moved them again hoping the original signal would return but it did not. I figure either it was a fluke or there is a loose connection somewhere. I inspected the wires for breaks, even pulled off additional wire loom and electrical tape and found no problems. I inspected O2 connectors for corrosion, etc. but again saw nothing wrong. Perhaps there is an internal break in a wire that cannot be seen visually or the connector is not making proper contact. I'll keep playing with it to see what happens. I may take the connector out and just hardwire the sensor in.Thanks for listing those diagnostic steps. looks like some of them require a specific scan tool, which I do not have. I will follow the ones I can do and report back. I did check for exhaust leaks previously and found none.

Related Buick Questions