Okay, I have a 2006 Honda accord with a PO141 error. (Engine warning light on dash comes on )
I’ve taken it to the Honda dealership and they replaced the oxygen exhaust sensor downstream, but after they test drove it the engine light has come back on.Honda has advised me it is a fault with the ECU and the cost to replace is $3000.
Which I didn’t go ahead withI purchased a replacement ECU from the wreckers, installed myself and got it reprogrammed to get the car going again, but after all this, the engine check light still comes onI’m at a loss on what to look at next. Are there any Honda gurus on here with some advice? Thanks, Justin.

 

If the new O2 sensor is still good out of the box, then you need to troubleshoot the wiring and electrical connectors. Do you have a volt meter and/or a 12V test light?

 

Thanks for the reply.
Better still I plugged my OBD11 reader into the vehicle and did a test of the sensors and they all pass. Is there something else I should test
I took a video, And attached the linkhttps://share.icloud.com/photos/088C...oAFGDa1RQP-oXg
This vehicle now has a new oxygen exhaust sensor and now a new ECU that has been re-programmed and still coming up with the dash light fault and code PO141

 

The O2 sensor has two parts. The sensor part detects oxygen only when very hot. The heater part turns on when the car is started to heat up the sensor part, so the sensor can detect oxygen quicker and reduce emissions. The exhaust will eventually heat up the sensor to operating temperature and the sensor part will still work, and is why you are getting good readings with your scan tool when the engine was running.

The problem you have is with the heater circuit that is a simple circuit and setting the P0141 (the 0 is zero and not the letter O for searching this forum or the web). The heater circuit uses two wires (#3 and #4 on the picture below), where #4 has 12V power and #3 is ground through the PCM. If your 06 is like my TSX, the secondary O2 sensor connector is under the passenger seat. Please verify the wire colors, because the #4 is also labeled blk/yel on a later pic.

Use a volt meter and measure the voltage with the key in the II position between #3 and #4 on the engine harness side. If you have no voltage, measure the voltage between #4 and a good known ground (any bare metal bolt) using a volt meter. Let us know what you find.

 

The O2 sensor has two parts. The sensor part detects oxygen only when very hot. The heater part turns on when the car is started to heat up the sensor part, so the sensor can detect oxygen quicker and reduce emissions. The exhaust will eventually heat up the sensor to operating temperature and the sensor part will still work, and is why you are getting good readings with your scan tool when the engine was running.

The problem you have is with the heater circuit that is a simple circuit and setting the P0141 (the 0 is zero and not the letter O for searching this forum or the web). The heater circuit uses two wires (#3 and #4 on the picture below), where #4 has 12V power and #3 is ground through the PCM. If your 06 is like my TSX, the secondary O2 sensor connector is under the passenger seat. Please verify the wire colors, because the #4 is also labeled blk/yel on a later pic.

Use a volt meter and measure the voltage with the key in the II position between #3 and #4 on the engine harness side. If you have no voltage, measure the voltage between #4 and a good known ground (any bare metal bolt) using a volt meter. Let us know what you find.

 

Thanks for the reply
yes I have a volt meter and will try this
I think I will need to remove the seat to access the connection
Its Monday here today and I have a busy week ahead , but will post my readings in the next weekend or so when I have time
thanks stay tuned

 

I’m getting a voltage from terminal 4 to an earth

Terminal, 1 green/black Terminal, 2 red/white Terminal, 3 black/white Terminal, 4 black/red

So I disconnected the sensor and got my voltmeter out today, and I’m definitely getting 12 V between number four and an earth, but when I put it between these two terminals, ( 3 and 4 ) the volt meter is fluctuating all over the joint and not giving a clear reading

 

The blk/red wire at terminal 4 is good based on your testing.

You have a problem with the blk/wht wire at terminal 3 from that connector to the PCM at pin B19. The issue is most likely a broken wire but could still be the PCM. The PCM is less likely since you already replaced it.

For me, the next step would be to peel back a bit of the electrical tape and use a piercing probe to see if you get a voltage reading just past the connector to rule out the connector. Option B is to use a piercing probe just before the pcm at the blk/wht wire at pin b19 and see if you have a ground when measuring voltage. Plenty of youtube videos on pine hollow diagnostics or southmain auto on using piercing probes to test faulty wiring. I'd use the volt meter instead of the test light for now, since you are getting bad ground reading just using the volt meter. It is a safer test to protect the pcm.