[bashea]

2001 Rav4.
45,000 miles.

Got the CEL/P1155 code.

Checked sensor heater resistence, it's ok (2.6 Ohms). Checked fuses, relay, voltage from ECM. All ok.

Cleared code. Drove for several hours, street and highway, no CEL. Parked, and after 15 minutes at idle, the CEL light comes on.

I've repeated this a couple of times, and get the same result: CEL light comes on after idling for a while.

WHAT IS GOING ON?!

 

[DPFAST]

It looks like you may have problem with your A/F sensor heater core. Bank 2 sensor 1. Check it's resistance with an multimeter. Here is a good video on how to do it; https://youtu.be/_Kr-c8eBl5E

 

[Dr. Dyno]

I'd suggest checking the sensor's resistance right after the CE light comes on and everything it still hot.

 

[DPFAST]

I would also check the freeze data to see what are the condition for the MIL to come on

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[bashea]

DPFAST -

What is "freeze data"?

I have a BlueDriver diagnostic scanner, but not sure which PID is the most important to monitor:

Short term fuel trim?
Long term fuel trim?
Sensor voltage?
Lambda/Equivalence ratio?

Or something else?

 

[DPFAST]

DPFAST -

What is "freeze data"?

I have a BlueDriver diagnostic scanner, but not sure which PID is the most important to monitor:

Short term fuel trim?
Long term fuel trim?
Sensor voltage?
Lambda/Equivalence ratio?

Or something else?

It's called Freeze Frame Data and when your check engine lite comes on the computer takes a snapshot of your vehicle's parameters during the engine light event. https://youtu.be/du2pfGMzw-k

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[bashea]

DPFAST:
Thank you for the Freeze Frame tip!

Here's the report:

Trouble Code Triggering Freeze Frame:
P1155: A/F Sensor Heater Circuit (Bank 2 Sensor 1)
Freeze Frame Data:
• PID : Description : Value
• 03 : Fuel System Status : System A: Closed loop - using all oxygen sensor(s) as
feedback for fuel control System B: Closed loop - using all oxygen sensor(s) as
feedback for fuel control
• 04 : Calculated Engine Load Value : 14.9 %
• 05 : Engine Coolant Temperature : 88 °C, 190 °F
• 06 : Short Term Fuel Trim Bank 1 : -2.3 %
• 07 : Long Term Fuel Trim Bank 1 : -2.3 %
• 08 : Short Term Fuel Trim Bank 2 : 0.0 %
• 09 : Long Term Fuel Trim Bank 2 : 0.0 %
• 0C : Engine RPM : 711 rpm
• 0D : Vehicle Speed : 0 km/h, 0 MPH
• 0F : Intake Air Temperature : 68 °C, 154 °F

However, I don't know how to interpret this data to pinpoint what's going wrong.

Do you see what is causing the DTC to be triggered? Is Bank 2 Sensor 1 bad?

Again, it only happens when parked and idling for a long period of time (15+ minutes).