Are O2 sensors Honda, NTK, or Denso? If not, that might be the issue.

 

Denso

 

Two things come to mind.

First, make sure your wiring harness going back to the body of the CR-V is undamaged--a twist or nick in the wire could cause an intermittent connection.

Also, a random code could also mean that the catalytic converter is failing. The difference between the front and rear sensors indicates catalyst efficiency.

Remember the code that is being generated is only due to the ECU expecting a certain range of values. So it can be anything in that chain causing your error--bad wiring, corroded terminals on the connectors, bad sensor, catalyst efficiency too low, etc. The codes do not point to a bad sensor--they only point to something in that circuit that is outside the range the ECU is expecting. The service manual has a complete diagnostic procedure for each error code. It sometimes help to skim over that and see if there's anything else you can check in that circuit.

 

What is the code? P0420?

 

What does the short term fuel trim and long term fuel trim look like?
Just looking for what the engine is doing

 

I don't remember what they are. Do a Google search and I'm sure you will find the values

 

Will throw this out.

O2 sensor before cat will have variable readings depending on throttle position. That indicates the differing gases coming out of the combustion chamber.

O2 sensor after the cat will have a steady reading, which indicates that the cat has purged the exhaust to create a clean, homogeneous gaseous mix. Fluctuating readings by the after O2 sensor may indicate a bad cat. As Wildcat says, there may be other causes for this problem.

Best of luck in this matter. Please inform us when and how you resolve it. You will be helping others with the same problem.

 

racer5150 said that he replaced the cat/con.

In this case, we need to ask "was that an aftermarket piece, used OEM, or new OEM"?

we really need to know the present CEL code.

 

Alright so was able to clear the code today prior to driving it at hwy speeds for 60 km. Code was p0139 02 sensor circuit slow. Live data for stft between +05-+18. Ltft was about 10ish. Yes was a new cat plus sensors. Cat is a bosal. I've never been able to track down this lean cause through out the time I've owned the vehicle. Vehicles got about 300000km on her now. Over last year vehicle has had all new denso coils, Ngk iridium plugs plus all new injectors. I cleaned out the map sensor last fall but still ran 10+ ltft. Intake gasket? Also checked the valve clearance this winter and adjusted to spec still nothing. On the trip no code and had normal fuel economy

 

First of all, the downstream sensor has nothing to do with your fuel trims; that is if your LTFT is high (meaning PCM is enriching the mixture) the downstream sensor being "slow response" is irrelevant. The downstream sensor is ONLY for monitoring catalyst efficiency. The upstream sensor (sensor 1) is the one that the PCM uses for fuel control. Running just a tad rich on the LTFT could indicate an intake leak somewhere if it's at idle; if it's the same cruising down the highway at 2000 rpm, it's not an intake leak, though it could be a dirty MAF sensor. You didn't specify the year of your car so not sure if it has a MAF or not. All the newer ones have MAF sensors as they're significantly more accurate in measuring incoming airflow to the engine.

 

It could be a vacuum leak. Like an intake gasket. You could spray throttle body cleaner where it could be bringing in extra air. If the idle changes while spraying a certain area that would be the source of the leak.

 

Good to know what fluid. I usually use starter fluid to check for leaks but it's always been on snowmobiles or boats. Just curious tho would there not be coolant leaking somewhere also with the intake leak or I guess it depends where its leaking on the gasket

 

Yeah it would depend where. If you are losing coolant I would say definitely

 

Just curious how shitty a job is it to take the intake off. Just gotta drain the coolant and remove everything before the intake ie the air intake/throttlebody?

 

With the ECM trying to compensate for lean condition,
this might be a cause for failure for the catalytic converter??

Something needs to be done.
Checking for vacuum leaks is a good idea.
Don't forget to clean the MAF sensor.
Check the IAC valve, clean as necessary

When the engine is cold, the ECM will use a fuel map stored in the ECM.
The ECM will use this map during open loop.
When engine is warmed up and goes into closed loop, the ECM uses the O2 sensor
The up stream O2 sensor is used to modify the air/fuel ratio mixture.
The timing of the PWM of the fuel injectors is adjusted accordingly
The down stream O2 reads the efficiency of the catalytic converter

Removing in-take? Look for youtube videos.

 

With the ECM trying to compensate for lean condition,
this might be a cause for failure for the catalytic converter??

Something needs to be done.
Checking for vacuum leaks is a good idea.
Don't forget to clean the MAF sensor.
Check the IAC valve, clean as necessary

When the engine is cold, the ECM will use a fuel map stored in the ECM.
The ECM will use this map during open loop.
When engine is warmed up and goes into closed loop, the ECM uses the O2 sensor
The up stream O2 sensor is used to modify the air/fuel ratio mixture.
The timing of the PWM of the fuel injectors is adjusted accordingly
The down stream O2 reads the efficiency

I thought the throttle body was electric on this model so no iac valve. If this is electric does it need to be calibrated. Something I'm assuming I'd need honda to do

 

Removing the intake probably isn't too bad. I can't tell you by experience on the CRV. Watch some videos on it. They are like free shop manual

 

Smoke test before manifold removal would be a good option.

 

It is a drive by wire (electric). I wouldn't think it would need calibrated. As far as I know the computer calibrates on its own

 

Throttle body may be electric. Does not mean it couldn't use a cleaning.
But, right now, not sure how it relates to your issue.
P0139 slow O2 sensor bank 1 sensor 2
The down stream sensor is not functioning correctly

The upstream sensor is an air/fuel ratio sensor
The downstream determines the efficiency of the catalytic converter
An air/fuel ratio O2 sensor can respond a little slower than a regular O2 sensor
Is it possible that the O2 sensors were accidentally switched?
Or are the fuel trims real and this is causing the deviation is the O2 sensor readings?

Sorry, at a loss right now.