V8 - Check Engine/P0031

[DC runner]

Hey Gang:

Searched and want a verification. 1. The v8 has 1 cat, correct? The v6 has 2?

Or is that wrong? I popped a check engine today. Pulled the code and it is p0031, which is, if I am correct should be the Bank 1, Sensor 1 heater circuit. This could be loose or bad sensor.

The bank 1, sensor 1; on the V8 is Drivers side above the cat, correct? I should be able to get to it through the driver wheel well?

Just looking for verification.

Edit: Actually, upon looking. On the v8, the bank 1 sensor 1 is behind the cat?

 

[DC runner]

ok. Actually, after pulling the TIS and Service manual.. I am more confused now. Someone who knows, can you help. This is a case where TOO much info is killing me.

The v8 has 1 cat converter and the v6 has 2. But, does the V8 have 2 upstream sensors or just 1?

 

[chaz]

number of cats depends on year for v8 (pre vvt-i or not) V-8 4Runner headers - Group Buy - Toyota 120 Platforms Forum

 

[chaz]

heres a pic that may help. http://www.toyota-4runner.org/4th-gen-t4rs/89785-o2-sensor-replace-p0031-code.html

 

[Belovian]

P0031= O2 sensor heater control circuit low Bank 1 sensor 1

To start, regardless of how many O2 sensors or even cylinders any vehicle has, Bank 1 sensor 1 is Always the Pre cat sensor, on the side of the engine where cylinder 1 is located. In your case, most likely the heater inside the O2 sensor is broken, pretty common.

Just for reference

bank1 sensor 1= pre-cat on same side as cylinder 1
bank1 sensor 2= post-cat on same side as cylinder 1
bank2 sensor 1= pre-cat on opposite side as cylinder 1
bank2 sensor 2= post-cat on opposite side as cylinder 1

good luck


Jesse

 

[Levinz11]

Refer to DTC P0130 on page 05-60 .
DTC No. DTC Detection Condition Trouble Area
P0133
P0153
Response time for heated oxygen sensor’s output voltage to
change from rich to lean, or from lean to rich, is 0.9 sec. or
more during idling after engine is warmed up (2 trip detection
logic)

Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit

Heated oxygen sensor (bank 1, 2 sensor 1)

Heated oxygen sensor heater (bank 1, 2 sensor 1)

EFI relay

Air induction system

Fuel pressure

Injector

ECM
HINT:

Bank 1 refers to the bank that includes cylinder No.1.

Bank 2 refers to the bank that does not include cylinder No.1.

Sensor 1 refers to the sensor closest to the engine body.
WIRING DIAGRAM
Refer to DTC P0130 on page 05-60 .
INSPECTION PROCEDURE
HINT:
Hand-held tester only:
The narrowing down the trouble area is possible by performing ACTIVE TEST of the following ”A/F CONTROL”
(heated oxygen sensor or another can be distinguished).
(a) Perform ACTIVE TEST by hand-held tester (A/F CONTROL).
HINT:
”A/F CONTROL” is an ACTIVE TEST which changes the injection volume to -12.5 % or +25 %.
(1) Connect the hand-held tester to the DLC3 on the vehicle.
(2) Turn the ignition switch ON.
(3) Warm up the engine with the engine speed at 2,500 rpm for approx. 90 sec.
(4) Select the item ”DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/ A/F CONTROL”.
(5) Perform ”A/F CONTROL” when idle condition (press the right or left button).
Result:
Heated oxygen sensor reacts in synchronizing with increase and decrease of injection volume
(+25 % " rich output: More than 0.55 V, -12.5 % " lean output: Less than 0.4 V)
NOTICE:
However, there is a few second delay in the sensor 1 (front sensor) output. And there is about 20 seconds
delay in the sensor 2 (rear sensor).
059VB-01

 

[DC runner]

Thanks all. Going to check the electrical connection first, but I suspect I simply need a new sensor.

I am all about OEM for sensors and will grab a DENSO OEM and throw it in there somepoint this week.

 

[DC runner]

I am correct in assuming a bad heater circuit in an O2 sensor won't blow the engine up if I drive around a week on it? As I have mentioned before, I live in D.C. and it is illegal to work on your cars on the street. I don't have access to a private driveway.

My next door neighbor, who is also my friend, is a Marine and has access to Bolling Airforce Base garage. Apparently for 7 bucks an hour you can use the facility, which includes full vehicle lift racks and all the tools you could dream of. Great deal.

He will go with me next weekend to change it out. I was looking to do it here, but I cannot get at it from the engine bay. Probably need to be under the truck...

My neighbors give me the royal stink EYE when I am under it. I live on a pretty up scale street. People who pay other greasy handed people to do all their work for them.. so the sight of a dirty knuckled dude crawling under a truck is "unslightly" to them. They *****ed at me when I changed my oil. Didn't have 1 drop of oil hit the ground, but oh well.

So. I will wait a week to deal with this. I don't commute to work, so during the week the truck is mainly my "groceries" runner 1 a week. I am assuming that in that short of time, and miles; no damage will be done. I may get worse MPG, but that is it...