2001 Solara surging P1135

[wills55]

Ok heres the problem:
2001 Solara V-6 with approx 100k miles, Automatic
The car has performed flawlessly for the last 5 years. Routine maintenance has always been done my me and never a hint of trouble until a couple days ago.

I had the CEL come on while driving then within seconds, the car started surging and bucking violently. I pulled over, shut the car off. Started it back up and drove on down the road for about 10 minutes @35-40mph.I stop at a stop sign and when I start off again, it starts with the bucking and surging again. I take it to Autozone for the guy to run the code and all I get it the illusive and PITA P1135. I dont get it, how does an "Air/Fuel sensor heater circuit response (bank 1 sensor 1)" cause this? It is my understanding that his is not much more than an oxygen sensor and shouldnt cause this huge of a driveability problem. I cant go anywhere in this car. Its down right dangerous. Can this sensor really cause something like this? Ive got a 1999 Avalon in the driveway that I can borrow parts from to solve this mystery so Im open to intelligent suggestions. Thanks folks.

[chronoti]

nope search for a vacuum leak, and as a note p1135 is the sensor closest to the firewall before the cat

[wills55]

I knew it was ridiculous to think that that A/F sensor could cause such a problem. Thank you for telling me where it is. I will replace it tomorrow.

I just came in from outside and found that the PCV valve and hose were completely out of the valve cover on the rear cylinder head. Im thinking that its probably a pretty big freaking vacuum leak, however....

It doesnt explain why the problem seems to come and go as it pleases. See, even with the PCV valve completely out of the valve cover, I was able to drive the car around my neighborhood for about 10 minutes without issue. The car was cooled down some but still at operating temperature. So as it may seem Ive found my culprit, there is a question in my mind that it may not be the problem. Any ideas other than checking for vacuum leaks.

[chronoti]

the thing with the pcv valve is that it is a valve that will not open until the system is under high enough vacuum.

[Jason.MZW20]

Originally Posted by wills55

It is my understanding that his is not much more than an oxygen sensor and shouldnt cause this huge of a driveability problem.

Well, it's not just an oxygen sensor. It's a wide-band oxygen sensor or air-fuel ratio sensor.

P1135 will cause bank 1 to run in open loop, so if you have an abnormally reading MAF or a vacuum leak (as stated), that bank won't have fuel trim correction, which can lead to drivability issues. Toyota says that the long-term fuel trims are used in open loop on certain vehicles.

Open loop operation uses the MAF reading and pre-programmed values in the ECU. If bank 1 is receives more air than the MAF suggests (dirty MAF, vacuum leak), the bank will run lean, and you'll experience surging/bucking and a general loss of power.

The CA emissions/2001 ECUs try to stay in closed loop the majority of the time. I believe I've registered closed loop up to about 50% absolute throttle position (70-75% is fully open). Otherwise, they are in closed loop, so they rely on the AFR sensors more than the older ECUs that use traditional lambda/O2 sensors.

[wills55]

Understood. I guess thats why its $170 instead of the regular $98 02 sensors Im sued to buying. So, you are suggesting that my newly discovered PCV valve leak combined with a faulty A/F sensor could indeed cause a violent bucking/surging issue? Is it possible or even remotely likely that I might replace the PCV valve and grommet, fixing my vacuum leak and the bucking/surging issue might go away? Ive also just realized while typing this that the fuel mileage has gone straight down the drain in the last few days. When the car decides to start its rodeo ride, I can mat the gas pedal to the floor and the car shows no indication of accelerating, downshifting or increasing the RPM.

Im thinking, I should replace this PCV valve so that I can rule out the vacuum leak issue and see if that doesnt solve the problem. Unless my above statements have stirred anyones thoughts further.

[fenixus]

replace that AFR sensor if you still have a code for it after fixing PCV valve (replace the grommet too, old one is useless).

as above Jason explained, AFR sensors are crucial for driveability. with one bad AFR sensor, your car falls into a limp (failsafe) mode, your MPG will drop down and car will start following pre-defined fuel maps not based on real life sensor readings.

Get the Denso OE replacement (not universal one), this is what fits both the front and rear (firewall) bank on V6 (california emission specs)
Denso 234-9021
http://www.densoaftermarket.com/cata....php?part=afrs

cheapest on ebay or amazon, search by part number and make sure it says Denso in Manufacturer field and not some cheap brand pretending to be compatible (most of them are not worth a broken dime unless it's a OEM or Denso or NGK/NTK).

Amazon

Amazon

$104 free s/h

expect the front one to go bad soon after. they usually last no more than 150k miles, but can fail earlier (heater in it may fail prematurely).

the rear one (post-cat) under car usually is useless after 100k miles, it's the narrow band o2 sensor Denso 234-4137 if you'd like to replace it too. car uses it mostly for catalyst monitoring.

[wills55]

Thank you all for helping me figure out this issue. Its going to be nice driving the Solara again. Its only been about a week and I miss driving it already. For my sanity, allow me to ask one last thing if I may. Is the sensor Im going to replace the one closest to the cylinder head? I just want to make sure that I replace the right one the first time.

[chronoti]

yup

[fenixus]

P1135 is a heater circuit malfunction in AFR Bank 1 Sensor 1. it's the upstream sensor located in rear bank (by windshield, firewall).

borrow an oxygen sensor socket set from autozone (refundable deposit required) and also get a 3/8'' torque wrench (e.g. this one).
you should be able to access it from top after removing the intake hose and top of air box (and strut brace on Solaras).
torque on re-installation is IIRC 32ft-lbs.

Use PB Blaster on old sensor base where it meets the exhaust before you try loosening it with o2 socket.

oh and first unplug the old sensor from socket before you start screwing it out or you may damage the wires. it might be hard to accomplish with one hand reaching from top, but is doable.

[chronoti]

lol i cut the connector and use the closed end of a normal wrench, i do own the socket too just for this........

[fenixus]

I don't like destroying o2/afr sensors on removal.
I actually sold all of the old ones on ebay (all were OEM) because all of them were working still when I was replacing them with brand new ones (major tune up was the reason, not malfunction), I basically pro-rated the sell price based on amazon Denso OE pricing and avg limits (150k miles for AFR and 100k miles for o2)

besides sometimes, you replace the afr sensor just to discover that same error still happens on the new one (so old one was good as well) and problem could be the wires, or even ECU (very unlikely).

Originally Posted by chronoti

lol i cut the connector and use the closed end of a normal wrench, i do own the socket too just for this........

[wills55]

Again, thank you all very much for the help. I own the 02 sensor socket and have multiple torque wrenches. I just wanted to make sure I knew which sensor to replace before I get started.

[fenixus]

sounds good, good luck wills55

[Jason.MZW20]

Yeah, anytime the ECU reports an AFR heater code, it disables the heater and reverts to open loop for the affected bank only.

I also had P1135 and here's how my OBDII logger reported it:

Fuel system, bank 1: Open loop (driving conditions)
Fuel system, bank 2: Closed loop

STFT and LTFT on bank 1 were both 0.00%.

Regular O2 sensors only draw around 2 amps, while AFR sensor heaters draw up to 8 amps, so it's important for the electrical system that the ECU disable it.