2 AF sensors, Code P2237, and still the check engine light is on...

LINK........................here TIS

 

Thanks for providing those pages. I recall that my 2004 ECM and hybrid vehicle ECUs received firmware updates a few years ago, resulting from a TSB addressing driveability issues.

I still do not see why a used ECM could not be reprogrammed. What is the difference between a used ECM from a salvage vehicle with similar model year, vs. the original ECM installed in a vehicle several years old? If the latter can be updated with the latest firmware, why not the former?

For that matter, the OP might find that if her car's original ECM was reprogrammed, her problem might go away...

I understand the concept of reprogramming in order to update the ECM to the latest available firmware, but I do not think this firmware is specific to a particular VIN. Rather I believe it would be specific to a production date range.

 

They base everything off the VIN. If the car has an anti-theft system, it's not gonna work with the wrong info.
Some cars are Federal and some are CA emissions and that makes a difference. Mid year production changes also
make a difference. Any ECM will need to be programmed with the correct VIN as a minimum requirement.
Production changes can have a profound effect on internal architecture of the ECM and the wiring harness.
Pin-outs can change and components can be added. If you plug an ECM into the wrong vehicle, you cold smoke
the wire harness the ECM and/or both. Like I said. It's not a one fits all and you can't just buy an old ECM
It's a specific unit for that platform, emissions, production date and VIN.

The VIN is the key to every vehicle made. It contains all the information required to get the correct replacement parts.

 

I agree with your statements as generally applicable to most other cars. However pls note that with regards to Prius, there is no difference in emissions equipment between cars sold in CA vs. the other 49 states. All 2G Prius sold in the US are certified to pass California AT-PZEV emissions requirements.

This is why all 2G Prius have the silly fuel tank bladder, which was intended to reduce vapor emissions as part of equipment required for AT-PZEV certification. You do not, for example, see our Texas 2G Prius owners smugly telling Californians that in Texas there is no problem filling the fuel tank without the filling station pump clicking off prematurely.

If you look at any of the websites of Toyota dealers selling parts online, you can look up the 2G ECM and you will see that there is one ECM part number offered for sale based upon model year. You will not find one ECM being sold for CA vehicles vs. another ECM sold for 49 state vehicles, because they are all the same for a given model year range.

If you consult the Toyota techinfo Electrical Wiring Diagram for 2G models, you will not find one diagram for California vehicles vs. another diagram for 49-state vehicles. Again, this is because all Prius of a given model year are equipped with the same ECM, same emissions control equipment, etc.

If this problem happened to my Prius, I personally would have no problem buying a used ECM and installing it. Assuming the used unit has the correct part number and was functional when removed, the worst case scenario would be needing to have current firmware downloaded to it, while the best case would be that the car would become READY and no warning lights would appear.

 

Can you share what the final outcome is? I've got the same error...and have tried three different A/F sensors. Let me tell you...that getting to that sucker is a royal PITB. Wipers, motor, front drainage tray all have to come out...then you have to perform feats of gymnastics to get at the upper sensor.

Can you tell me what finally solved your problem? I'd hate to have to replace the ECM and/or the harness. My harness looks fine (cosmetically)...and my next step will be to check continuity back to the ECM.

Thanks!

 

Ok...the fine engineers at Toyota have me stumped with the same problem as Prius4ed. I am getting a P2237 code...and I am into this with three sensors now. Here is some background:

I’ve tried three different A/F sensors now. Two of them were eBay items from China (supposedly for my year/make/model) and one was a Toyota sensor. The two chinese sensors measure about 10ohms on the heater and the Toyota unit measures 8ohms. Before purchasing any sensors I measured the voltage/signal from the ECM to the A/F sensor and I am getting 12.8V DC with a PWM square wave on top of that. That’s why I went the route of replacing the sensors…figuring my harness and my ECM were working. Not sure where to go from here since I need to get my vehicle smogged…and I can clear the code just prior to the test…but figure they will see the pending error and I will fail.


Note: The problem started off with a catalytic converter error (I have since forgotten the code)…and learned that this was a red herring for the O2 sensor and/or the A/F sensor. So, I replaced both…and the error shifted to the P2237 which I can't seem to squash.


Thoughts?


BTW...if any of you have done this, you know what a royal PITB it is to get to (both the sensor and the plug).


Thanks!


Craig

 

You probably needed to only replace the catalytic converter, code p0420

 

If you want to continue to DIY, I suggest the next step would be to verify continuity of the wiring between the A/F ratio sensor wiring harness connector, and the wiring harness connector at the engine ECU. If you subscribe to techinfo.toyota.com you can access the factory repair manual info which shows you the relevant wiring connectors and pins.

By the way, the repair manual indicates that the resistance across the sensor heater terminals should be 1.8 to 3.4 ohms at 68 degrees F.

 

Hi! could you solve the problem?

Hello how are you ? I need your help! I see him as the person who knows the most about these cars! I have this same code, were they able to decipher what the fault was?

 

the problem was the motor pcm?

 

Patrick symptoms of a bad ecm on my 20008 toyota prius? I have reconditioned the battery cells discharge charge to over 8.0 volts per cell.
That didnt fix the problem, I take off the negative battery cable let sit a while, plug back in and the battery screen on the car showing 6 blue lines. after running a little while, driving a few blocks, the bars go down to zero or one purple bar showing, then the car starts running funny, misfire, low power, barely gets home.... The codes showing on my code reader are p2237, p3193,p00031, p0302...I've replaced the o2 sensor also, new injectors, spark plugs....

Nick

 

Did that ecm fix for your prius fix the problem still?
Nick

 

I had codes p0031 and p2237, a new Denso upstream O2 sensor fixed both.

+1 for the Schley 66750B, not removing the inverter and accessing the O2 sensor from below the car. I tried the tekton socket but it does not fit inside the shield off the sensor only the 66750B does.

I do all of the work on all of my cars, Took about an hour and a half in total. Cowel goes quick with an electric impact gun, the O2 sensor with 16 years and 182000 mi came off pretty easily, just warm up the engine first so the exhaust pipe expands.