Kermee

iTrader: (1)

Hi All,

I was doing a bit of search and I didn't want to thread jack an existing thread so this might be an easy question.

After a mild, but not brutal, acceleration in my 2004 GX470 this morning in the heavy rain, my VSC OFF, VSC TRAC and CEL lights came on and are staying illuminated. However, the SKID light is NOT on unlike some of the other reports.

I placed an overnight Amazon Prime order for an inexpensive OBD2 reader and it arrives tomorrow. From what I've read and with the mileage I have on the GX470, it could be the gas cap, O2 sensors, speed sensors, etc. But most of the reports shows that the SKID light was on too but mine isn't on.

Anyone have any ideas what it might be? Just curious before I'm able to pull the codes tomorrow. The vehicle drives fine though, granted obviously it's in 'limp' mode right with VSC disabled. Thanks in advance!

Cheers,
Kermee

P.S. I was spoiled with my Nissan Versa, before I sold it, being able to pull the OBD2 codes and clear them without a scanner by doing a little 'dance' and watching the CEL light flash out the stored codes.

Kermee

iTrader: (1)

Answering my own thread.

I got impatient and swung by O'Reilly's this evening and borrowed their OBD2 scanner. Single code came up: P0051 -- HO2S Heater Control Circuit Low (Bank 2, Sensor 1). -- I was hoping for a P044x but no luck

Found this great DIY thread here and OP remarked "The VSC TRAC, VSC OFF and Check Engine lights were all on." ... But not the SKID light. Bingo! My search foo was weak earlier today... So now I have to decide whether to diagnose the O2 sensor myself or just take it to my Lexus dealership. Looks like it's the upstream (Sensor 1) from what I've been reading.

Denso 234-4138 (O2 upstream L/R) is $56.63 from Amazon.com and the 'special' O2 wrench is $17.99 so I might go ahead and try to do it myself. Though I'm going to do a quick check underneath if maybe the O2 cable/pigtail was damaged or disconnected in the morning. From the other thread, the OP had his O2 B2S1 sensor go out at 105K in his '04 GX470 and my '04 GX470 is just shy of 102K on the original O2 sensor so I have a feeling it might be bad. I may just skip the diagnosing since all the parts I would need is easily only about $80 including shipping. I'm 99% sure the O2 sensor is bad.

Couple things I noticed before the lights came on:

#1. I did start noticing about two weeks ago that the GX470 had a rough idle. After starting her up, it was cycling back between 600-700 RPM's about every 7-10 seconds. I didn't think much of it then.

#2. Same two weeks, after driving almost 500 miles during that time, I was logging about a 2 MPG drop in my average MPG. I just attributed it to my driving style and since the temperature has dropped considerably lately, I thought it might be because my tires were running a bit low too. Turn out, the MPG drop might be due to a bad O2 sensor.

Cheers,
Kermee

Kermee

iTrader: (1)

Update #2: Parts ordered Next Day (Thank you, Amazon Prime!). I'm going to replace the O2 sensor myself. My Bluetooth OBD2 adapter arrived. Why didn't I get one of these earlier?!





Going to log my O2 sensors on the drive home.

Cheers,
Kermee

vince22

Got one earlier myself, just cant beat this Amazon $24 Blutetooth OBD2(ELM327) with Torque Pro app. Good luck.

Blanco

iTrader: (8)

Kermee,

Did the O2 sensor swap fix the issue?

Kermee

iTrader: (1)

I've been on vacation in Florida since the day before Thanksgiving and didn't get a chance to swap the new one in before I left. I get back in a few days so most likely will do it this upcoming weekend. I'll give an update then!

Cheers,
Kermee

Kermee

iTrader: (1)

Finally had a chance to put in the new upstream O2 sensor. Here's a picture of the new one (Denso) and the old one (Toyota OEM/Denso):



Took less than 15 minutes in all. More than half the time was spent to disconnect the wiring on the old sensor and reconnecting the wiring new sensor. (Long arms help).

I manually cleared the P0051 and disconnected the battery for a minute to reset the ECU. Rough idle is gone now and the engine is definitely running smoother. I took it for a 15 mile drive and the P0051 never came back. The trip computer showed MPG on test route to be 20.9 MPG vs. about 16.8 MPG when the O2 sensor went bad. I usually get around 19 MPG on average.

Cheers,
Kermee

eburggx470

Did the same fix on my 2004 GX470 for code P0051. Passenger side O2 sensor before the catalytic converter. I borrowed the special wrench but it was such a tight area that I couldn't get it to line up with the nut on the sensor. Instead, I disconnected the wiring connector and slid a 22mm 12 point box end wrench over the wiring. This allow me enough space to line up the wrench and make ~1/8 turns until it came out.

GreatHim

just got this code as well, ordered a new o2 sensor and will report back, i have noticed my mileage dropped off a bit over the last 4 months or so, i believe the o2 sensors in the truck now are the originals so its time to replace them, my questions is, should i replace both up stream o2(A/F) sensors or just the one?

GRAYM

How do you clear these codes?? I assume that once the problem is fixed they neared to be cleared. i have disconnected the battery a few times to reset it but the lights still come back on....thoughts??