Bassinfool

My CE light came on a couple months back, and I ran 4 codes:

P0171 - System too lean, Bank 1
P1135 - Air Fuel ratio (I believe)
P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control
P1130 - O2 Sensor Bank 1

I searched all these codes on here and decided to start with my MAF sensor. I got the cleaner, cleaned the parts per the descriptions on here, re-installed & cleared all codes. Within 2 miles the light was back on & still had all 4 codes.

This morning, I replaced the MAF sensor with a brand new one from Toyota. Also replaced the spark plugs (NGK's). I cleared the codes again and took it for a drive; the same loop I did last time. At almost the exact same point, the CEL came on again. I got home & ran the codes. This time I only have two:

P0125 - Insufficient Coolant Temperature for Closed Loop Fuel Control
P1130 - O2 Sensor Bank 1

I'm assuming the P1130 means I also need a new O2 sensor (pre-cat), and please correct me if I'm wrong. I'm checking here before I go spend another $200 on a part that won't fix my problem. But what about the P1130?

Any input? Thanks guys!

Specs are in my signature
|
|
V

Bassinfool

Just noticed my sig doesn't show up on the mobile site.

01 Tacoma 4wd
2.7l 4-cyl
K&N FIPK
Exhaust

goodyota

i would replace your coolant temp sensor (for the computer) since it has to do with air fuel ratio and set a code.

Bassinfool

I'll look into that. Just pulled the codes again after driving another 10 miles or so & got the P1135 again. I can't see the coolant temp sensor causing all 3 codes; am I wrong or could there be something else?

goodyota

the o2 sensor can SERIOUSLY mess with your A/F ratio so throwing a new one in should fix the majority of your problem, Also the coolant sensor increases the fuel mix until it knows the engine is at op temp then leans it out. so both sensors can F with A/F in their own way.

TheDurk

Do the O2 before thinking about the ECT. The ECM frequently throws the P0125 due to a bad O2. It knows one of the two is wrong but it is not sure which one so it throws both. I cured both a p0125 and a P1135 with just an A/F sensor. (I have a '99 Cali.) I would have cleaned the MAF and replaced the front O2 before replacing the MAF. Just the o2 might have cured all of those codes.

Bassinfool

A buddy of mine (who's automotive/electronics intelligence level is WAY beyond mine) said that a bad ECT will screw up your O2 sensor, so I should check/change that first. The question I have is this: would the ECT Sensor be similar to spark plugs, AFM, etc, where you want to use a Japanese part? The reason I ask is Toyota wants $85 for their ECT, whereas I can get one from O'Reilly for $30-$40. Any ideas on that one?