Hi everyone,

This is my first post. I can’t find an answer other than generic replacement, trace for shorts etc… Did ALL that. My son’s B2S2 heater throws P0161 code. I replaced, cleared the code. It came back. Traced for short and couldn’t find one. Reset the ECU via my scanner and it came back. Scanner shows that the heater is “OFF”. Am I missing something? Is there a way to have the ECU turn it on or do I need a new ECU?

 

What year accord and engine type (V6 or 4cyl) are you working on?

 

2010 V-6 iVTEC

 

Your PCM may be advanced enough to shut down the O2 sensor heater once you get the code. If you clear the code and cycle the key, the PCM should try a test on the heater circuit by sending voltage for a short period of time, so maybe a few seconds. Some testing with a volt meter to see if you missing the 12V power source or the ground wire. The ground side goes directly to the PCM and the PCM detects current or voltage returning from the O2 heater to determine if it is working. Your scanner might have the ability to power on the bank2 sensor 2 heater circuit for testing purposes as well. You have some data PIDs showing B2S2 voltage and duty cycle, so you may want to just observse those readings to see if something seems off. You can compare to B1S2 for a known good reference.

I'd start by hooking the volt meter to a good known ground, then test each wire for battery voltage when you turn the key to the II position.

I'll also suggest that you purchase a shop manual for your car to help with wire colors and wiring diagrams. Automanualsource.com has a V6 pdf for a 2010 that you can purchase for $22 and is worth the investment IMO. I don't have a 2010 V6 manual, so I can't help with wire colors and specific wiring.

 

I rest the computer through the scanner, tried the battery disconnect, etc. the code comes back pretty quickly. So it’s either a short I can’t find or an ECM issue.

 

I only have the 08-10 4-cylinder shop manual, but I'd suspect the setup is similiar. The heater circuit is pretty simple. Think of the heater as a bulb connected to the + and - of the battery to generate heat to warm up the O2 sensor, so it can optimize gas usage/emissions.

I was wrong on my first post. The + side of the heater comes from the ignition switch in the 1 or 2 position and powers a bunch of other items. The - side from the heater is grounded by the PCM. So the heater should always have 12V on the + side. The PCM isn't seeing or can't see the current return and displaying that the heater is off on your scanner. If you had a dead short on the + side, I'd suspect a fuse would be blown. I would probably use a volt meter to see if the O2 sensor heater is getting 12V to at least split the circuit in half.

That shop manual I referenced earlier will have some diagnostic trees that will identify the wire location on the connector and wire colors. The troubleshooting steps in the shop manual are average at best. I try to understand what the shop manual is trying to accomplish on each step as well. I eventually use the wire colors and some basic tests to figure out what could be wrong.