I’d appreciate any help in how to find the meaning of an OBDII Mode $06 CID $01 TID $2E. Does that refer to a specific part that was tested by the ECU/PCU? This is from a 1998 Accord LX 2.3L automatic. This car currently has the CEL set and a P1457 code. It got that after 50 miles of driving after replacing the emissions control two-way valve, which was replaced due to a P1456. I am planning to change the evap canister vent valve to try to fix the P1457, but would really appreciate help with the Mode $06 info. Car has 242K miles on it but still runs well.

 

Usually the 1456 code is the vent shut valve. A 1457 code is usually a loose or not sealing gas cap.

 

Fuel cap is recently replaced with Honda part. I've had the car for 20 years and still remember to tighten the cap 3 clicks, but glad we got that one out of the way, as it seems to be everyone's reasonable first thing to try. The P1456 went away after replacing the two-way valve. I found fuel in the two-way valve when replacing it. Again, no longer have the P1456. Now have P1457, but planning to try replacing the vent shut valve for that. Thanks for the suggestions.

 

I’d appreciate any help in how to find the meaning of an OBDII Mode $06 CID $01 TID $2E.

 

Mode 6 is the self diagnostic checks the PCM does. I'm pretty sure these are called readiness codes.

From a quick web search is the $2e is the PCM commanding the EVAP system to purge.

 

Thank you for the help. My unsuccessful web searching found what looked like a need to purchase a data subscription for Mode 6 info, which may be worth it, but that remains difficult to tell. I have not seen any positive user reports, just marketing info. I tried searching again and got better results, including info similar to what you provided.I found a document named It appears that this is a percentage, $2E EVAP_PCT (%) COMMANDED EVAPORATIVE PURGE (%). I wonder what the numerator and denominator are in this percentage. Based on my prior post, It looks like the minimum value is 8, which I take to mean 8%, and my car scored 0% and thus failed.

Much of the earlier web searching indicated P1456 must pass before P1457 can be tested. I’ve seen these at times described as P1456 indicating a large leak and P1457 being described as indicating a small leak. Alternatively I have seen P1456 described for my 1998 Accord LX 2.3L auto as indicating a tank side leak (between two-way valve and tank) and P1457 as a canister side leak (between two-way valve and purge control valve). This design was supposed to help isolate failures, but web searches suggest that it turned out otherwise, and two-way valves seem to have been engineered out of the design. I was hoping mode $06 would provide additional insight.

Replacing my two-way valve did change things from P1456 to P1457, so I may have had a large leak and now have a remaining small leak. Since I have ordered the Canister Vent Valve, I will go ahead and replace that, at least it is part of the canister side description of P1457. Perhaps I should have also changed the bypass solenoid when I changed the two-way valve, but that is more expensive than the two-way valve plus the Canister Vent Valve.

It would be nice to not have to guess. I’ve read about smoke tests, but cannot find the green capped service port on my car, if there is one. The tool is also expensive.

 

I found an interesting document named GlobalOBDVehicleCommunicationSoftwareManual_EAZ002 5B43.pdf. The document provides a description of EVAP_PCT. It seems that EVAP_PCT shows the duty cycle of the purge control valve, where 0% indicates no flow.Why would I have a 0% duty cycle for my purge control valve?

I found this:
I am not aware of a fuel trim issue, but how would I know if I did have one?

After clearing the code and two drive cycles, I have another P1457, but this time there are two Mode $06 failures.I noticed that the Component Id is $00 for the TID $18 issue (it was CID $01 for TID $2E). The helpful document lists a few possible descriptions of TID $18, so which one applies to my 1998 Accord LX 2.3L Automatic?Thanks for any helpful advice!

 

I had this on a 02 civic...it was the rubber seal holding the sending unit on tank under the rear seat.loosened it and fixed seal and cranked it back on..

 

Be careful with the "failed" test, because you might not have completed the entire drive cycle to pass the test. I don't know the criteria to pass the test.

Work on the P1457 first, since you have the code. Then worry about the $18 later. $18 looks like the secondary O2 sensor heater circuit from a very quick google search.

 

PAhonda – thank you for following this thread. I agree with the recommendation to pursue the P1457 first based on that being the OBDII code that I have.

I had P1456 when this saga began, and that changed to P1457 when I replaced the two-way valve. When I replaced the two-way valve, there was liquid fuel (gasoline) inside the old part.The P1457 then became very predictable; clear the code, drive the car twice, MIL comes on and code is P1457.

This morning I decided to remove my fuel cap before starting my engine. The whoosh of air (or fuel vapor) that I heard when opening the cap made it quite clear that it had been air tight. Should it have been air tight? I could not tell if the whoosh was releasing vapor pressure, or if perhaps I had a vacuum inside the tank due to lower temperature overnight. I thought the Canister Vent Valve should have been open while the car was parked overnight, and the two-way valve should have been allowing fuel vapor into the canister while the canister vent should have let air escape to the environment. It was clear that there was either pressure or vacuum.

Given how predictable getting a P1457 had become, I wondered if I could get the P1456 back by simply storing the gas cap in the trunk (could have just left it at home) and driving. I was surprised to find that the MIL did not come back after several drives, but I do have a pending P1457.

Here is some wild speculation that fits the facts. Maybe I overfilled my fuel tank and that caused fuel to make it to the two-way valve. That valve is designed to function with air and fuel vapor, but not with liquid gasoline. Maybe I have liquid fuel trapped between the tank and the two-way valve, and maybe driving without the cap for a day helped some of that dry out. I put the cap back on (to avoid water vapor condensation inside the tank), but will remove it again in the morning. I’ll try to figure out if I have pressure or vacuum. I’ll drive another day with the cap off. I have the freeze frame data from the pending P1457 and will capture that if I the MIL comes back on based on a second P1457 detection.

Or maybe I had a large leak that was fixed when I replaced the two-way valve, and now I have a small leak. Perhaps it is time to obtain a smoke machine and figure out how to use it. Is there a smart choice amongst tools on the market? Where would I find the green cap service port on my car?

The criteria needed to pass the test (and positively affirm repair) appears in some online documents, but seems rather difficult to pursue. I know that my 10 mile drive to work is adequate to produce the failures that I have seen so far. I’d be happy to get through two tanks of gas without such a failure.