Replace One Sensor to Clear All Codes? ('99 es300)

[tjdean01]

Hello.  We just picked up this es300 in very good condition.  We took a trip and during that trip, the overdrive stopped working.  We made it home in limp mode, I disconnected the battery, reconnected, and the car has been driving fine for a few days now.  Checked at O'Reilly's and there is no code for the knock sensors, which is apparently often the problem when the car won't shift into 4th gear.  But, the no-overdrive problem seems to occur at times when the coolant sensor, engine sensor, thermostat, etc., isn't performing/reading correctly.  So, I figured I should address the codes I'm getting now and see if the no-overdrive problem returns (yes, someone removed the check engine light so these didn't pop up when we bought it):

P0125 - Insufficient Coolant Temperature for Closed Loop Fuel Control.  After extensive reading, it seems that this code hardly ever occurs by itself and often resolves itself when you resolve another issue. So, I think we should wait on this and address the others first.

P1130 - Air/Fuel Ratio Sensor Circuit Range/Performance Malfunction Bank 1 Sensor 1.  B1S1, I believe, is behind the engine near the firewall.  After reading a lot online, I think that if the B2S1 is replaced, this code might go away

P1153 - Air/Fuel Ratio Sensor Circuit Response Malfunction Bank 2 Sensor 1.  This is the sensor right up front.  I'm thinking that changing this might fix the other codes as well.  Or, this is the best place to start, I'm guessing.  

P1155 - Air/Fuel Ratio Sensor Heater Circuit Malfunction Bank 2 Sensor 1.  Again B2S1, the one in the front of the car that's easy to get to.

So, I guess I could buzz it over to my dad's house for him to check electrical continuity; or to figure out if the sensor's heater is working properly.  However, I'm thinking simply replacing the sensor might be the best bet.  

If I do change this sensor (B2S1), what is the Toyota part number?  And, I've heard to not use off-brand parts for knock sensors, but since this is not a knock sensor, can I buy something locally at AutoZone that's readily available and comes with a warranty?  

I'll probably do as you guys recommend.  Much appreciated!!

 

 

 

[tjdean01]

Well, I've done a lot more reading and got some advice and will post it here for future users.  I haven't done the fix yet but here's my plan:

The P0125 coolant temperature code is usually slave to the either of the O2 sensor codes.  I believe there are three O2 sensors: 1 after the cat which I don't care about (and I'm not getting a code for anyway), and the two by the engine.  As you can see above bank 1 sensor 1 is behind the engine (and I'm getting a code for it - P1133).  But I'm hoping this is also a slave to bank 2 sensor 1, for which I'm getting the two codes (P1153, P1155).  As this is my GF's car and not mine, and since I only have time on the weekends, I'm not going to do the most logical thing and just replace the bank 2 sensor 1 (the easiest one to get to...in the front).  I will replace that, but I will do it in addition to other things, because once I'm in there, I might as well do it all.  

I found the B2S1 (Toyota OEM #: 8946741011) used on ebay for $20.  New is $150 for OEM, or I could get a new off-brand.  Good choice or bad, who knows but that's what I bought (if I had more time I would have found one in a junk yard for $5...at least the seller says he tested it and has 1000s of positive feedbacks).  I bought the coolant temperature sensor too.  New OEM was $25.  I might not even put it in if that code goes away immediately after the O2 sensor change and a few quick drives around the block.  If it doesn't, I'll just change it.  $25 and plug & play is easier than getting someone with a multi-meter to test it.  I could learn how to test it but again, I'm pretty busy.  Finally, the thermostat.  Unlikely its bad, but I bought a new OEM one.  $19.  I wouldn't have bought this because my "test" shows that it's working: engine stays cool and we have hot heat for an extended period of time.  But, the car's operating temperature gauge, which should be about half way, is only around a quarter of the way.  Good, right?  Maybe, but what if that means the exhaust is cooler?  Will my cat still catalyze?  Probably as the engine produces friggin' fire, but again, it won't take me long to change it.  At least with this repair I'll know if it did anything.

So, a careful, logical man makes his choices.  $75 is nothing versus running all over town opening the hood every day.   I hope the parts arrive by Saturday though.  I'll post the results!

PS: the overdrive "fix" of removing the battery and plugging it back in is still working!  She's been driving it since the problem occurred Sunday (today is Thursday).