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Check engine light on our 2005 Honda CRV

The check engine light on our 2005 Honda CRV (146,000 miles) came on and stayed on. After a week of driving with the light on we brought the car to the dealer to have it checked. The dealer diagosed a faulty catalytic converter given a P0402 diagnostic code and didn’t think the P1078 code for the intake manifold a problem. The dealer also stated that the oxygen sensors were fine. We declined the dealers offer to replace the catalytic converter for $2,170 and the check engine light was reset. After two weeks of daily drifing and 1000 plus miles the engine light is still off. Did we actually have a problem? Why hasn’t the light come on again?

Good that you didn’t spring for a new cat. I have a 99 CRV with its original cat and have never had a problem with it. I also had an 88 CRX for 15 years and 175k+ miles, and never had a problem with that cat either.

As long as the lights stay off and the engine seems to run OK, forget about it and drive on.

A P0402 code is for Excessive Exhaust Gas Recirculation, not the catalytic converter. A P0420 is a code for the cat.

If you had a P0402, then you did the right thing. If it comes back, then the DPFE Differential Pressure Sensor is probably the cause, although the EGR valve may be stuck open, something blocking the valve from closing completely.


If it was a P0420 code, again you did the right thing, but in this case, it will come back eventually. When it does, you can turn off the light again. when it starts coming back on in less than a week, then there is a high likelyhood that the rear oxygen sensor is bad. In this case, you should get the dealer to order a new sensor based on your VIN number.

I’ll assume that this vehicle is well beyond its warranty period. In that case, there is no need to take it to a dealer.

Ask around among people you know for a good, locally owned, independent shop. If the light comes back on take it there.

I’ll assume that the code was P0420 and that the 0402 was a typo or something. In addition to checking O2 sensor operation one also needs to check for exhaust leaks. The P0420 does come from anomalous readings from the rear O2 sensor, so every other cause has to be eliminated before moving on to a converter replacement. If it does come to that you probably don’t need to spend $2K - unless you’re at a dealer.

Yes, the code is P0420, sorry about the typo. What would the code be for a bad oxygen sensor?
Could the P1078 code for the intake manifold have caused the P0420 code?
Our gas mileage is still good at 24mpg.

You just want the light to be off for your next emissions test, if you are required to get an emissions test. Otherwise, keep your wallet in your pocket and drive on…

It’s the downstream or rear oxygen sensor that throws the P0420 code…If you MUST spend some money, change that first…

Thanks all, we’ll just wait and see if the light comes back on.

Be sure to Google “P0420 Honda CRV”. Other owners in various internet forums may have this same problem and may have found some simple solutions already.