Power6

**If you don't care about my stories and just want to see a possible cause of P1135 and P1155 just skip down to the bottom!

Hope everyone is well. Can't believe I still have my ES, 6 years and nearing 160k and I bought it with 85k. That's like forever for me to keep a car lol.

Anyways I had a code recently come up P0330 for the #2 knock sensor. Car wasn't quite in limp mode but not driving well. Following the factory testing procedure of swapping the wires between #1 and #2 indicated the knock sensor was bad. These are a bit of pain to replace, underneath the lower intake manifold, the wisdom in Toyota circles says replace the wiring harness and both sensors, and only use the OEM stuff. The sensors are ~$150/ea. Since I am a poor disadvantaged entrepreneur I picked up just one OEM knock sensor, but I sprung for the wiring harness too. I'll take my chances on the #1, too much cheddar for me to replace a still good part. At any rate I got it done. I disconnected just what I needed to on the upper and lower intake and lifted them up suspended with a couple coat hangers to get this done without physically disconnecting and removing both pieces.


All went well and the code went away, but I immediately got 2 new codes. DAMMIT lol. P1135 and P1155. Air-fuel sensor heater circuits for CA emission cars. (my car was bought and lives in MA so follows CA emissions). Apparently these thing are real sensitive. Now what are the chances both sensors went bad right after I took a bunch of stuff apart? I figured not bloody likely! Sure I must have missed connecting something. But nothing obvious. I started looking at the harness, that goes around the motor, the knock sensor plug is really hard to free from that...maybe I damaged the harness? But what are the chances just one wire...boy I would be screwed I am not putting a $1500 harness in this car. So I left it overnight and went back out this morning...thought about this, the code is set when the resistence of the heater circuit is too high. I could get out my volt meter but think about this grounding is really key and there are a few ground wires that connect to the upper intake. One of them is a real PITA to get to at the back facing the firewall. I started with the easier one on the side, pulled it off, sanded and brushed the hardware, mounting surface and terminal. Put it back, cleared the codes and...same codes right away on start. OK fine lets do the PITA one in the back, pulled it off and cleaned it up the same. Cleared the codes...WOOHOO its been running all day and they haven't come back! That must be the ground for the A/F sensor heater circuit. Funny how just removing and replacing introduced enough resistance to cause a problem. Always a good idea to clean ground wire interface before you reattach them. I was just lazy and never had that type of thing happen to me before. Maybe this being here in the search will help someone else with the same issue someday...

TL;DR if you got both code P1135 AND P1155 at the same time, after you check the A/F heater fuse, also check the ground wire interface at the back of the upper intake, especially if you have taken stuff apart and put it back there.