# 2002 Honda CR-V Codes P1164, P0420, P1078



## wrbrb (Aug 18, 2020)

My 2002 CRV with 110,000 miles is showing current codes of P1164 (Primary HO2S (#1) Circuit Range/Performance), P0420 (Catalyst System Efficiency Below Threshold (Bank 1)), and P1078 (Unknown/Intake Manifold Tuning Valve System Malfunction - High RPM).

The catalytic converter is about 5 years old (previous one stolen) - I need to get these errors resolved so I can pass my emissions test and re-register the car. Could someone help me figure out what to test to fix these issues?


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## huesmann (Aug 18, 2011)

Start with replacing the upstream O2 sensor. Then try replacing the IMRC valve.


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## wrbrb (Aug 18, 2020)

huesmann said:


> Start with replacing the upstream O2 sensor. Then try replacing the IMRC valve.


Thanks, I was actually leaning toward the upstream O2 sensor (aka A/F sensor?) but didn't know if there was a testing procedure prior to spending $150 on the part. But I am seeing this as a common failure on these vehicles.

Regarding the IMRC valve, again I would rather not remove the intake manifold to replace the costly valve unless I know that's it. Does the IMRC solenoid ever cause this issue, and can it be tested?


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## raylo32 (Nov 25, 2006)

Here is a good video of a guy diagnosing his IMRC valve. He had an additional code, P1078.

HONDA CR-V IMRC REPLACEMENT / diag. P1078 P1077 2006 2.4L how remove replace acura rsx - Bing video


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## HotRodx10 (Aug 24, 2017)

wrbrb said:


> but didn't know if there was a testing procedure prior to spending $150 on the part.


You can take it in for an engine diagnostic, but that will probably cost about the same $150. 

I didn't have enough info to find out for sure, but it looks like you should be able to get the O2 sensor for under $50.


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## LawrenceS (Oct 21, 2020)

wrbrb said:


> My 2002 CRV with 110,000 miles is showing current codes of P1164 (Primary HO2S (#1) Circuit Range/Performance), P0420 (Catalyst System Efficiency Below Threshold (Bank 1)), and P1078 (Unknown/Intake Manifold Tuning Valve System Malfunction - High RPM).
> 
> The catalytic converter is about 5 years old (previous one stolen) - I need to get these errors resolved so I can pass my emissions test and re-register the car. Could someone help me figure out what to test to fix these issues?


p1164 there may be a PCM update(20 year old TSB 02-028) but since updates overlap, if you've ever had the PCM updated recall or otherwise it may have already been updated.

But there is also a vin range of effected models 
2002 CR-V With 2WD
From VIN JHLRD6...2C000001 thru JHLRD6...2C019081
From VIN SHSRD6...2U000001 thru SHSRD6...2U001812
2002 CR-V With 4WD
From VIN JHLRD7...2C000001 thru JHLRD7...2C067524
From VIN SHSRD7...2U000001 thru SHSRD7...2U008787 

An A/F sensor can cause false cat codes, but it would have had to set the cat code first as a p1164 should prevent the cat monitor from setting.

Sorry don't have time to jump into the IMRC issue right this second(at work currently).


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## wrbrb (Aug 18, 2020)

VIn ...2C014990, so appears to be within range, but I have no idea if previous owners would've taken it to a dealer for a PCM update. I don't suppose I can check that somehow myself with limited equipment (Bluetooth OBD2 reader) or if there's a database a pro can access?

Would it be worth trying the A/F (upstream O2) sensor first, and see if that resolves the cat codes? I would hate to try that and then kill that brand new sensor if there's a different issue (although maybe that's more of an issue on the downstream O2 sensor?).

Regarding the IMRC, the linked video showed removal and cleaning of the valve assembly itself, but if I could get away with replacing the solenoid that would be preferred from a labor standpoint. Then again I don't have any vacuum gauge or pump to test the solenoid or function of the existing valve itself even if I did want to pull the manifold and clean it.

Any more guidance is greatly appreciated but I'll try to find some time soon to investigate hoses for the IMRC and wiring in both areas. Thank you!


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## LawrenceS (Oct 21, 2020)

wrbrb said:


> VIn ...2C014990, so appears to be within range, but I have no idea if previous owners would've taken it to a dealer for a PCM update. I don't suppose I can check that somehow myself with limited equipment (Bluetooth OBD2 reader) or if there's a database a pro can access?
> 
> Would it be worth trying the A/F (upstream O2) sensor first, and see if that resolves the cat codes? I would hate to try that and then kill that brand new sensor if there's a different issue (although maybe that's more of an issue on the downstream O2 sensor?).
> 
> ...


Probably not with a code reader and there are no databases it's just by using a scantool on the vehicle. With the factory scantool software the PCM(or PGM-FI as honda calls it) section displays the program PN and/or the update tool software, maybe an actual scan tool would but I can't say for sure. It looks like the original software part number was 37820-PPA-A52 or sometimes they display just as like PPA-A520 and TSB's will be like update to 37820-PPA-A53/PPA-530 or latest available like 37820-PPA-A54(or higher) but this one is so old they just say make sure your update software database is up to date and update the PCM. It's not that the it will kill the brand new sensor it's just sometimes driving conditions can make the sensor read out of it's preprogrammed range so the sensor is working properly it's just the initial R&D didn't cover enough time or diversity in environment to account for how big the acceptable range should be or possibly slight sensor degradation but it's still working well enough to not screw with 

It's not uncommon to have A/F sensors fail, so it could be worth a shot. Though I would suggest only going with an NTK sensor(subdivision of NGK and pretty much all Honda A/F sensors are actually made by NTK) you can get one on rock auto for like $212. Denso makes a lot of stuff for Honda too, but not typically the A/F sensors and it is a little cheaper at $130. One precaution though depending on where you live there is a chance the bung in the pipe is going to have the threads rip out while removing it, though typically with an o2 sensor thread chaser you can reshape them well enough to install a new sensor. Actually I just realized you said you had the cat replaced so if it's an aftermarket cat it might be aftermarket sensors too(whatever brand was available by whoever replaced it) and if it is an aftermarket sensor it's probably a good chance it is the sensor. Though Honda's often don't like aftermarket cats and there is also a good chance it might set a cat code again and/or if it's an aftermarket downstream.

The way the 2 sensors and the cat work are the upstream is an a/f sensor or as tuners call them wideband o2 sensors, which are more accurate at detecting the exact oxygen level in the exhaust vs a regular o2 sensor which just tells if it's high or low. Honda uses A/F sensors to adjust how much fuel it's adding(can't say if other manufacturers do the same or if they just use intake based sensors to adjust fuel and o2 sensors are just for converter monitoring). Vehicles are designed to have some o2 in the exhaust to allow it to react with unburn hydrocarbons(gas/petrol) to go from o2 and hc to co2 and h2o and to turn co into co2, it measure cat efficiency by how much oxygen is left after the cat(well in your case the downstream is in the middle of the cat) a proper functioning cat should eliminate a lot of the o2 to get rid of the hc and co, when they fail you end up with to much o2 reaching the downstream sensor.

Still have to read into the IMRC more to give you a proper answer, the rest of this was just off the top of my head.


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## wrbrb (Aug 18, 2020)

Thanks for the detailed feedback! You definitely know your stuff if that's mostly off the top of your head. My main concern is passing the emissions test, which I think I might have passed two years ago with the intermittent IMRC issue. The testing facility noted that any check engine light, however, would be an immediate fail, and then I would need to have the vehicle repaired at an authorized facility before I can renew the registration. I'm thinking my best bet right now if I take the "throw most typical parts at it" approach, would be the AF sensor for $130 and the IMRC solenoid for $120, so that's not terrible. But it would be great to diagnose that the right way, too.


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## LawrenceS (Oct 21, 2020)

wrbrb said:


> Thanks for the detailed feedback! You definitely know your stuff if that's mostly off the top of your head. My main concern is passing the emissions test, which I think I might have passed two years ago with the intermittent IMRC issue. The testing facility noted that any check engine light, however, would be an immediate fail, and then I would need to have the vehicle repaired at an authorized facility before I can renew the registration. I'm thinking my best bet right now if I take the "throw most typical parts at it" approach, would be the AF sensor for $130 and the IMRC solenoid for $120, so that's not terrible. But it would be great to diagnose that the right way, too.


I'm kind of like the sheldon cooper(big bang) of Honda techs but I've only been working on Honda's for 8.5 years and the last year of IMRC was 06 I've had to troubleshoot a couple but we typically don't see that many older vehicles at the dealer so I'm not super familiar with them. I think I've done 2 of the runner assembly's but none of the solenoids. If I get some time I'll try to look into the IMRC more, but working 13 today, 11 tomorrow and 10 sunday so not a ton of free time.


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## huesmann (Aug 18, 2011)

HotRodx10 said:


> You can take it in for an engine diagnostic, but that will probably cost about the same $150.
> 
> I didn't have enough info to find out for sure, but it looks like you should be able to get the O2 sensor for under $50.


IDK why, but while the d/s one can be had for the $50 you mention, but the u/s sensor is $150.


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## raylo32 (Nov 25, 2006)

How's about we call you Honda Yoda?



LawrenceS said:


> I'm kind of like the sheldon cooper(big bang) of Honda techs


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## HotRodx10 (Aug 24, 2017)

huesmann said:


> IDK why, but while the d/s one can be had for the $50 you mention, but the u/s sensor is $150.


The upstream ones usually include a 'preheater', so sometimes they're more. On Amazon, I saw a set (u/s & d/s) for $57, but they're aftermarket. I've never had any problems with aftermarket parts, but some people only want name brand or 'OEM'. OEM can be a misnomer, though, since many 'OE' parts, including O2 sensors, come from 3rd parties, anyway.


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## huesmann (Aug 18, 2011)

Yeah, we discussed that in this thread. It looks like the Amazon aftermarket ones are the Chinese brands with the names created by throwing letters at the wall and seeing what sticks.


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## LawrenceS (Oct 21, 2020)

huesmann said:


> IDK why, but while the d/s one can be had for the $50 you mention, but the u/s sensor is $150.


Different style sensors, upstreams are air/fuel sensors not oxygen sensors, they have different internals and generate a signal differently and more accurately over a wider range. Oxygen sensors are kind of "dumb" sensors, like .1-.3v lean, .7-/.9v rich but not precise in their measurement. Reason being is they are used to adjust the injector duty cycle to fine tune the air/fuel ratio in conjunction with the Mass Airflow Sensor, Intake Air Temp sensor, Manifold Absolute Pressure sensor, Barometric Pressure sensor and Engine Coolant Temperature sensor.

Pretty much all Air/Fuel and Oxygen sensors these days use heaters.


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## HotRodx10 (Aug 24, 2017)

LawrenceS said:


> Pretty much all Air/Fuel and Oxygen sensors these days use heaters.


I guess I was misinformed. Thanks!


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## wrbrb (Aug 18, 2020)

Just as an update in case it's relevant - I found the paperwork from Midas (I was desperate) from when the catalytic converter was stolen, and it was in 2017, so about five years ago that the cat and sensors were replaced. It just says "16167 Converter Direct Fit" and "234-4125 oxygen sensor" as well as "234-9005 air-fuel ratio sensor". 

If I replace the AF sensor, could it be immediately damaged by a bad cat, or is that impossible?


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## LawrenceS (Oct 21, 2020)

wrbrb said:


> Just as an update in case it's relevant - I found the paperwork from Midas (I was desperate) from when the catalytic converter was stolen, and it was in 2017, so about five years ago that the cat and sensors were replaced. It just says "16167 Converter Direct Fit" and "234-4125 oxygen sensor" as well as "234-9005 air-fuel ratio sensor".
> 
> If I replace the AF sensor, could it be immediately damaged by a bad cat, or is that impossible?


If the cat was bad like plugged or had started to break apart causing it to plug up you'd most likely have some drivability issue caused by excess exhaust back pressure.

That's pretty much the only way a bad cat could damage the sensor would be a chunk of the honey comb rattling around inside the exhaust. I mean if your burning oil, that could contaminate the surface of the sensor and cause it to read incorrectly and it could cause the cat to go bad. Even when vehicles need legit cat replacement, I've replaced some that don't really look messed up inside. Cats have a fine ceramic honeycomb with rare metals in the ceramic(assuming metal dust that is mixed in the liquid ceramic before the honeycomb is cast), the metals at the catalysts, a catalyst is something that reduces the energy needed for things to react without being used in the reaction. I'm going to assume failure's are either the ceramic gets surface abrasion over time and the metal dust is exhausted or something coats the ceramic preventing the metal from being in contact with the exhaust gasses not allowing it to act as a catalyst.

As for why aftermarket ones don't work well in Honda's, I have no idea how they are designed/tested, but I would speculate either they use less rare metal or their testing equipment is calibrated to federal/cali regulations and not the specific Honda programming, so they end up not performing in the acceptable range of Honda programming.

The walker cat could be part of the issue for the p0420 code, and the A/F sensor is a denso, so either the sensor isn't working to Honda's spec or something has caused it to fail, or it could be excess resistance in the PCM or wiring harness skewing the voltage the sensor is generating causing it to read out of range, or it's the PCM update issue.

The A/F and o2 are Denso's according to the Part numbers, so either their point of sale software has pregenerated part numbers from some catalog that uses denso PN's and they sourced other brand sensors(no way to prove without seeing their bills from their parts suppliers and i doubt they still have them from 5 years ago) but it shows the PN from their software or they used Denso sensors and you might be better off trying an NTK.

Most likely it's either something killed the sensor like burning oil, the sensor isn't an NTK so it's just not performing to the same spec or the PCM software.


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## sestivers (Aug 10, 2007)

My impression is that the aftermarket catalytic converters use much less of the active (expensive) materials than an OEM unit, and that is a big reason they cost less. And that would make them last not as long. 

You could do a rudimentary evaluation of the catalytic converter performance by watching a simultaneous graph of the upstream and downstream oxygen sensor voltage outputs... if the downstream graph similarly follows the upstream, that would indicate that the catalytic converter isn't doing much of anything to the exhaust gases. You can do this with the free Torque android app and a cheap ($10) OBD2 Bluetooth transmitter.

It's also true that oil burning can reduce the catalytic converter lifespan.


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## wrbrb (Aug 18, 2020)

Here's what I have from the upstream and downstream O2 sensors. How does this look?

Idle:









Driving down the street:


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