griffithbuilt

I have been getting a P2000 check engine light on my '05 Honda Civic Hybrid and I have two questions:

I am not sure what the code means. ALL (4) of my scanners (An Auto Xray, CarCode Serial Logger, PLX Kiwi Wireless and DashHawk) all say it means NOx Trap Efficiency Below Threshold. Which directs me to look at the O2 sensor outputs which are alarming...voltage levels on O2 sensors are high for rich, low for lean. Sensor 2 is between the cats, Sensor 3 is aft of the second cat. My second sensor is chronically higher voltage (by 50mv or so) than my forward sensor. When I warm the cats up (spirited driving, etc), it goes way beyond that.

Now the OBDII reports a short term fuel trim capability for both the second and third O2 sensors and the second fluctuates mildly between -2 and 2, probably normal. The third is pegged at 99%.

So I'm guessing due to it registering more rich than the two in front of it, that it has failed and that the failure mode is to do something that the computer will see and flag (like fail rich). The cat isn't rattling or anything so I don't suspect it at this point.

The rub in this while dilemma is that a few places online show a P2000 code as a 'Hybrid Battery System Voltage High' code.

Is anyone here a shop tech who can help me out to either validate my assumption here about the tertiary O2 sensor or verify/deny the P2000 code as a 'Hybrid Battery System Voltage High' issue?

Thanks,

Jason

Markllb2002

I have the EXACT same problen with my 2005 HCH! What did you do to fix it? I don't believe it's my catylatic converter either. I'm more inclined towards the o2 sensors but I can't figure out which one with Palmer ScanXL Pro. What did you find out?

Markllb2002

Oh I didn't mention that I had all ready replaced the the bank1 sensor 2 o2 sensor. It's still reading high after replacement.

Mui_Fofu

I have a '04 HCH and im getting a p2000 aswell, just like the previous guys i DONT believe its my CAT & strongly believe its the O2 sensor, anybody know which ones normally go out first and how to replace them?

Thanx,
--Frank

gearbox

iTrader: (95)

the first o2 sensor (closest to the engine) is the most important for how the car runs. but looking around online, it sounds like bad EGR valve, which is responsible for reducing NOX emissions by recirculating some exhaust back to the engine. hybrids have a much lower tolerance for polluting, so even a small clog of the valve can trigger the code. try cleaning it with carb cleaner, otherwise if that doesnt work you need a new one and the gasket too.

http://www.greenhybrid.com/discuss/f...-05-hch-23716/

if that doesnt work, this one says you need a new second cat (for NOX emissions).

http://honda-tech.com/showthread.php?t=2714882

this guy said new cat fixed the p2000 code (altho i would only recommend going with an oem honda cat. the cheap ones will not last long at all).

http://townhall-talk.edmunds.com/dir...ew/.f115f58/60

also another thing to remember is that the cat converter has an 8 year/80k mile FEDERAL mandated warranty. so if you qualify, take it to the dealer and have them put a new cat on for free... if they refuse, they can be fined thousands of dollars for the violation and you can get the gov and epa involved.

this guy says the cats have issues and dont last as long as they should in a normal car. having a cat go out this soon is crazy

http://townhall-talk.edmunds.com/dir...ew/.f115f58/79

if the egr valve cleaning or replacement doesnt work, my money is on the cat. and hopefully you are still under the warranty.