Well Azine, maybe you guys can help me out. I've been having a really rough time with my car lately and as if things weren't bad enough I get a check engine, VSA and ! light popping up. Well, after going to autozone and discovering code p0131, normal instincts tell me to buy an o2 sensor. I decided to get a bosch universal one, slapped that on... and lights still come on. Well, fustrated and angry... I went ahead and got the denso(234-4727) sensor and light is stillllll on.

I need help and am up for any suggestion. Anything you guys can recommend like the o2 sensor imitator or w/e, I just need this problem solved and it's pretty much stressing me out.

p.s. I have a prosport narrowband A/F gauge and it pretty much reads flatline lean, needle down, when it use to bounce like crazy.

 

Just to make sure, you are replacing the front 02 and not the one by the cat right?

Next thing i would check is the wiring.

 

yessir, the one in the front.
Wiring as in, the part that connects from the (enginebay?) to the o2 sensor itself?
Because the Denso one is just plug and play.

 

DTC P0131: Primary HO2S (Sensor 1) Circuit Low Voltage


1. Reset the PCM.

2. Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on.

3. Check the primary HO2S (Sensor 1) output voltage with the scan tool during acceleration using wide open throttle.


Does the voltage stay at 0.5 V or less? YES - Go to step 4.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the primary HO2S (Sensor 1) and the PCM.n

4. Check the fuel pressure.


Is it normal? YES - Go to step 5.

NO - Repair the fuel supply system.

5. Turn the ignition switch OFF.

6. Disconnect the primary HO2S (Sensor 1) 4P connector.

7. Start the engine and let it idle.

8. Check the primary HO2S (Sensor 1) output voltage with the scan tool.


Does it stay at 0.5 V or less? YES - Go to step 9.

NO - Replace the primary HO2S (Sensor 1).

9. Turn the ignition switch OFF.

10. Disconnect the PCM connector C (31P).

11. Check for continuity between primary HO2S (Sensor 1) 4P connector terminal No. 1 and body ground.


Is there continuity? YES - Repair short in the wire between the PCM (C16) and the primary HO2S (Sensor 1).n

NO - Substitute a known-good PCM and recheck. If the symptom/indication goes away, replace the original PCM.

 

99 TL.
So i have been have this problem for a while where when I start my car it's idles very low and if I don't hold my foot on da gas or it will turn off. Didn't happen all the time but now it happenes almost every time. So Then this morning my check engine light came on. . Took her to auto zone n codes is p0131. Does that make any sense. Note: I jus did my valve cover gasket n plugs. Gasket was leaking bad. .. Help! Jus starting New job that a good drive away. Should I be worried?

 

Hey TL99sincere, a couple of things to check with a '99 would be the EGR passageways and have the fuel pressure checked. Could be a restriction in the fuel supply or intake. Check all electrical and vac connections. Put some fuel system cleaner in the tank and maybe even do a tune up with new NGK plugs and an air filter.

 

I did just valve cover gasket, ngk plugs, I cleared day port on the intake manifold to the egr valve. I also have a aem short arm intake. I cleared the code n it hasn't come back as of yet. But low idle sometime when I start it. I have hold da gas pedal n wait for a min or so n I'm ok. What u think?

 

Check vacuum connections. Could possibly be the IAC valve sticking ?
Try cleaning it along with the throttle body.

 

I got P0132 code - the engine was confused and behaved abnormally - so I got both upstream and downstream sensor from amazon

Denso 234-4727 Oxygen Sensor (upstream) $54
Denso 234-4621 Oxygen Sensor (downstream) $29

they are perfect fit for 2001 TL. you need an open end 7/8 wrench for the replacement. it was not that easier to loose the old bolts but under the car you can use your leg instead of arm (leg is always bigger than arm) to push the wrench to get it off.

the code error is gone and engine runs much better - I used to smell the gasoline from the exhaust but not anymore so the engine burns more efficiently.

2 cents:
1. don't buy the oxygen sensor socket from amazon or HFT as it won't work for 2001 TL due to space constrain for the upstream sensor (you can use the socket for downstream sensor though). an open end 7/8 size wrench should be able to do the job;
2. if replace, then replace both as PCM need reading from both sensors (and compare the difference?) so it's better to have both sensors replaced at the same time.

I consider this to be a very worthwhile replacement for 2001 TL.

 

Curious about how to check the output voltage if it's unplugged? Step 6 I think. Also curious about in step 9, I think, why would you repair an open circuit if you have continuity?