CEL Help

New here, recently picked up a 2000 Tacoma Ext Cab SR5 4x4... Stoked on the purchase. Typical drove away after test drive/purchase and the CEL hit me. Been addressing this and other areas of the truck since the purchase but this has stumped my friend and I. Any input is greatly appreciated...

Scanner show's Bank 1 Sensor 1 pending code, at the time was told this was the only code. Replaced O2 Sensor before Cat. No fix, check Live Data through Scanner. Shows there is no communication with the Sensor (bank 1 sensor 1). Checked the harness, sensor has power in and out... another run through the codes and its showing "Fuel System Lean" with the remaining pending code for the sensor.

Tomorrow I have planned to change the fuel filter and check the pressure from the fuel pump, but was also told it could be an issue with the Cats? Trying to avoid a trip to Toyota, as well as enjoying learning my way around the new truck.

Might mention the truck has seen minimal use over the last few years...

Thanks in advance Fellas

 

What are the actual codes?

 

Was expecting the typical "my CEL is on. What's wrong?" thread, but good on you for actually trying first. I can't contribute in any way though.

 

Don't have them at the moment. Just know pending is the first 02 and the active code is saying the fuel system is too lean...

 

Update:

Replaced the fuel filter, noticeable and welcoming difference climbing the RPM's, and the Fuel system lean code has gone away. With that exit came a new code...

PO125 which I'm seeing is the Coolant temp sensor which also points back to the first 02 which I've already replaced?

Pending is still the System 1 Bank 1 A/F sensor with the code P0135.

At this point we are thinking clogged/bad injectors and or a MAF issue? Any thoughts?

 

@eon_blue any food for thought on this?

 

If it's the maf it's almost always going to be accompanied by code p0171 if that isn't present I would suspect the maf is good. These trucks aren't know for having the best injectors, it may be worth it to buy a set of injectors from the junkyard and send them to witchhunter performance to have the rebuilt and flow balanced. Best thing I ever did for my 3.4

You can check the resistance of the injectors with an volt meter, they should be between 12-17 Ω I belive, it's in the FSM. I checked mine when having a random reoccurring miss and my cyl 6 injector was at 48Ω!!!

It still ran quite well 90% of the time. After installing witchhunter rebuilt and flow matched injectors though, wow, the butt dyno could tell for sure HUGE improvement.

 

If it's specifying your A/F (air/fuel) sensor then I'd look into replacing that. Like mentioned above, the MAF sensor typically throws a P0171 code

 

Replaced the thermostat, code has remained however before the code displayed the system was open... now its saying the system is closed... Replacing the ECT sensor this afternoon. Hoping this will resolve the issue.

 

Have now replaced the ECT sensor and the issues remain:

P0125 - Closed Loop (Went from open to closed with thermostat replacement)
P0135 - Bank 1 Sensor 1 Fault (Replaced 02 Sensor/checked harness. All seems good unless I got a faulty OEM sensor)

After flushing/replacing coolant along with the thermostat, cold start has now started to drop and fluctuate in RPM's... where as before it would hold around 1200 nicely until it idle'd down. Any opinions and or suggestions are welcome.

 

What about the A/F sensor?

 

Replaced the sensor the code called for... code remains

 

Hmm reading into the code a bit it seems like it's related more to the 02 sensor which you've already replaced. Have you replaced the heated oxygen sensor fuse?

This is the link I pulled up, if you haven't seen it already:

https://www.google.com/amp/s/www.autocodes.com/amp/codes/p0135.html

 

Man you guys are really loading up the parts shotgun. Oi!

@GettingOut is this a V6 or I4 were working on?

As for the idle issues have you cleaned the idle air control valve and throttle body?