Planning road trip & now truck is throwing codes 401, 471 and 135

[canman]

On Friday, my CEL came on. Yesterday, I connected my scanner and it showed P0401 (EGR Flow Insufficient) and pending P0471 (System Too Lean - Bank 1). I cleared them, and today on my way to work the CEL came on. I just got back home, and now I got P0135 (O2 Sensor Heater Circuit Malfunction - Bank 1 Sensor 1) and the same code pending. I was working on the truck yesterday and I did disconnect the front O2 sensor which I reconnected. I need to have the truck ready for a road trip by Wednesday (800 miles), and I would like to know if I need to replace either of the O2 sensors. Is Bank 1 Sensor 1 the forward sensor? I did replace the front one two years ago with an NTK one, so it should be good, or maybe the wiring is no good. Any help would be much appreciated.

 

[94SRUNNER]

Well if it was OEM you could test it to factory specs. Seeing as it is aftermarket, I would look for specs online of call there tech support to see if the they have a test method to find out whether or not it is in working order. Otherwise you need to replace the unit.

 

[canman]

Well if it was OEM you could test it to factory specs. Seeing as it is aftermarket, I would look for specs online of call there tech support to see if the they have a test method to find out whether or not it is in working order. Otherwise you need to replace the unit.

I thought the NGK/NTK were OEM? I used P/N 24557. I just took the connector apart for the forward snesor, cleaned with brake fluid to get rid of some dirt, and now the silicone seal has swollen and I can't get the the connector back together!

 

[86tuning]

With Denso sensors you can measure the two black wires on the sensor with an ohm meter, you should get something like 11ohms resistance. If there is infinate resistance, you likely have a failed sensor or wiring to the sensor, which is popular with sensors that require wire connections.

On the NTK, if there are two wires the same color, measure those. There may be a white pair or a gray pair.

Failed heater circuit inside the sensor means you need a new one.

Faulty heater circuits do NOT mean your engine will blow up with a road trip, but the sensor may be lazy, which may impact your fuel economy. So I'd change it before the trip.

I prefer Denso sensors, which are OEM for Toyota.

 

[d0ubledown]

yep. toss the ngk's and replace with oem direct plug in ones from either cdan or sparkplugs.com (they ship to canada via USPS). as for the P0401, dont sweat it until you get back from your road trip...if ever. unless you have smog testing, i wouldnt botherl...

 

[canman]

Thanks for the input.
I managed to get the connector back together using a small screwdriver to push the silicone seal under the mating connector. I noticed that the four "breather" holes on each of the sensors was covered with dirt which I removed with dental type pick. I cleared the codes, and drove for 40 kms and no CEL. I know its not far but so far so good.
If I need new sensors, I'll order the Denso sensors when I get back (there're less expensive than the NTK ones at sparkplug.com).

 

[canman]

I thought that I would post an update for those having similar codes. I got back home yesterday after driving 1000+ kms (650 miles), and the CEL only came on briefly and then went out after starting and running the truck for approx 5-10 minutes after it had been sitting for a week at a hotel in Rochester NY. So before throwing out your O2 sensor(s), I suggest that you may want to have a look at the four "breather" holes and clean out any dirt that may have accumulated in them first.