The check engine light / engine management light on my Honda CR-V came on recently. Then it went off…then it came back on again…then it went off again. You can probably guess what happened next. In this post I’m going to describe how I worked out what was causing the light to be on, what had gone wrong (knock sensor) and how I fixed it (replaced the sensor).
The car in question here is a 2004 Honda CR-V with the 2 litre K20A petrol engine. This engine is found in lots of other Hondas (Accord, Civic, Stream Stepwgn), so hopefully this information will be useful for lots of people.
Obvious and less obvious clues something was wrong
Clearly the obvious clue was when the engine management light came on. Now I’ve fixed it, I realise the Honda had been giving me subtle clues that something wasn’t right for some time before the light came on. It wasn’t driving quite as it should, but also wasn’t quite bad enough or annoying enough to make me notice. Having fixed the problem, I now appreciate there was a slight hesitation when starting to accelerate from idle.
Finding the cause
When the light first came on I stopped as soon as I could to check for obvious signs (or smells) of woe under the bonnet and under the car. I suggest you do the same if this happens to you. In my case, everything was fine.
At this point I knew I needed to reach for a code reader. I used a Foxwell NT200 diagnostic scan tool.
This is a very cost effective unit but there are a couple of things to be aware of:
- It can only deal with ECU codes (i.e. not airbag, ABS or other electronic modules).
- It doesn’t do JOBD, so isn’t suitable for use on Japanese import cars. JOBD is a version of OBD2 for cars sold in Japan. Check before buying a code reader if you want to use it on an imported car!
Neither of these things were relevant in this situation.
If you haven’t used one of these code readers before, it is very simple:
- Find the OBD2 port. In this case it is in the driver’s footwell, above and to the left of the clutch pedal.
- Plug in the reader.
- Switch on the ignition.
- The code reader gets power from the car, so doesn’t need its own power.
- The code reader will communicate with the car’s ECU and report back on whether any codes are stored. It isn’t completely automatic so you’ll need to click through a few menus. This reader only has 2 buttons so you can’t go too far wrong.
- Navigate through the menus to read the code(s).
I was hoping to see a single code show up on the screen rather than a handful of codes, which can be more difficult to diagnose. Thankfully I was ‘rewarded’ with a single code – P0325, which refers to a fault with the knock sensor.
What is a knock sensor?
We should probably start by covering ‘knock’ itself. It is also known as pinking and refers to the noise produced when the air fuel mixture in the cylinder ignites at the wrong time (i.e. not in response to the spark from the spark plug).
If this keeps happening it can be bad news for your engine.
This is why engines have a knock sensor. This is bolted to the engine block and basically listens out for knocking. When detected, the ECU adjusts the ignition timing or air fuel ratio to stop the knocking.
Fixing Honda P0325 Code – Replacing the Knock Sensor
- Start by putting the car on some ramps so you can get underneath. A jack and axle stands will be fine too, but I find ramps quicker for jobs where I don’t need to take the wheels off.
- Lift the bonnet and remove the plastic tray underneath at the front. Be careful with the trim clips, but some will probably break anyway. You can use cable ties as a temporary fix if you need to wait for more to arrive.
- Find the knock sensor. It’s in a slightly tricky position on the front of the engine block. The internet is peppered with attempts to video and/or photograph its location. Here is mine! I this gives you a rough idea of the location. The picture was taken with the undertray removed.
- Check the wiring and the existing knock sensor are secure, so you don’t waste money on a new sensor if there is a simpler solution. In my case, they were, so on to the next step…
- …which was to research the likelihood of a fault with another component causing this Honda P0325 code. This is the second part of ‘trying not to waste money buying unnecessary sensors.’ I didn’t find a great deal of information to suggest this, so set about sourcing a replacement.
Time was not on my side – I was going on holiday in 2 days so didn’t really have time to order online and wait for delivery. So I contacted my local Honda dealer and was surprised to hear they had one in stock. This confirmed that faults with this knock sensor are common: they wouldn’t keep one in stock unless they sold / replaced quite a few. We won’t talk about how much it cost!
On to the replacement procedure. The instructions could be summarised as follows:
- Disconnect wire.
- Undo old knock sensor.
- Screw in new knock sensor.
- Reconnect wire.
Fairly straightforward then? Yes and no, depending on your patience, dexterity and the size of your hands. Let’s go through the procedure for Honda knock sensor replacement.
- Disconnect the battery negative terminal.
- Make yourself a coffee / tea / drink of your choice.
- Use hands or angled long nose pliers to release the wiring connector from the sensor and remove it. I did this bit with my hand, but this is tricky because you can’t see what you’re doing!
- Loosen the sensor with an open ended 27 mm spanner. You could also use a 27 mm socket with a universal joint on the end, but you may need to have the UJ only partially inserted into the socket, to give space for the electrical connector on the sensor. I used this job as an excuse to treat myself to a lovely Facom 27 mm spanner, which was a pleasure to use.
- Make sure the sensor mating surface on the engine block is clean and flat (i.e. remove any grease and rust).
- Screw the new sensor into position by hand.
- Tighten the new sensor to 31 Nm.
- Reconnect the wire to the sensor, making sure the connector clicks into place.
- Reconnect the battery.
At this point you can start the engine and (hopefully) enjoy the lack of engine management light on your dashboard. I connected my fault code reader prior to starting, fully expecting to have to delete the P0325 code, but it had already gone. This was a good result. Time to put the undertray back on and go for a test drive.
Honda P0325 Code Summary
We’ve now been through how to identify the Honda P0325 code as a cause of the engine management light coming on. We’ve looked at how to fix the issue by replacing the knock sensor, using the popular K20A engine in a 2004 Honda CR-V as an example. I found this a very satisfying fix. As well as getting rid of the engine management light, and any concerns about engine damage, it actually improved the driving experience too. There may have been a marginal improvement in fuel consumption, but it is difficult to say for certain because fixing this problem coincided with warmer weather.
I hope this information was useful for you. If anything wasn’t clear or if you’ve got a question, why not post a comment below?
My Honda crv 2004 also have knock sound inside the engine and light check engine also appeared, after I have used havoline oil, it just switched off the engine and the little smoke was coming out of dip stick oil hole, help me.
Hi
Assuming the oil was the correct viscosity and that the level is correct, I can’t see this being caused by using a particular brand of oil. It is very difficult to diagnose a fault without seeing the car, but this sounds like it could be a PCV fault. Have you done a fault code read to see which code caused the engine light to come on?
Cheers
Andrew
Thanks for taking the time to document this repair. Very useful information.
Thanks for the feedback Mike, glad it was useful.
Hi, just so during it this fixed the issue permanently? I had same error and replaced knock sensor, buyer for keeps popping up every hundred miles or so. I just reset the MIL and carry on ☺
Sorry to hear it! Did you use a genuine Honda knock sensor or an aftermarket one? Also I wonder if the wiring integrity is OK?
Hi there,
Thanks for this detailed walk through.
I’m going to attempt to swap this part out myself.
I don’t have a torque wrench. Will giving it a good tug be sufficient?
Thanks
Well, I’ve replaced the part and the engine management light has disappeared. I can attest to how awkward this job is. Getting old one out was easy. Getting new one in not so. Had to use a long extending magnet and try to turn it in using fingertips. After an hour and lots of cramp, swearing and cups of tea, it finally played ball. Hope I never have to do it again! Thanks again for your clear and useful guide.
Hi John
Brings back memories of when I did this job!
I’m really pleased you found my guide useful – thank you for taking the time to say so.
Cheers
Andrew
I used a 1/4 drive universal , the male end fits nicely into the plastic tube of the sensor, with a long extension to refit it, worked well to get it started in the thread.
Hi John
No problem, yes I’d say a low to medium strength tug would be sufficient!
Cheers
Andrew
Thank you for the article, very useful.
I have a 2005 2.0l CR-V
I diagnosed my problem with an ODBII scanner I purchased for +-7 pounds (NOTE: Some of these are Android only so make sure if you want iPhone compatible) and purchased the part on Ebay.co.uk. The number of knock sensors available to buy told me that this is a very common fault.
I managed to do this without ramps but did prop the front wheels up on two inch blocks of wood. Obviously judge the safety of this for yourself but even if these blocks failed there was no crush risk, it just allowed some extra elbow room.
I also chose to use a shifting spanner as I did not have a ring or open face spanner. I would highly recommend not trying this as it makes the job so much more difficult (twice the time at least). Buy the spanner!
I also did not have a torque wrench so tightened the sensor to about 50% of the pressure I would put on a spark plug. I reconnected the battery and the car has been running fine with no warning lights. This was an intermittent fault so time will tell if this repair worked or not.
Andrew
Thanks so much for the detailed information. My car is 2002 CRV and just 2 weeks ago the dealer here in Casablanca brushed me off after charging me for the diagnostics. When i asked why my engine light comes on they told me they ‘ cleared’ the error and nothing to worry about! On my way home the engine light came on again as i expected but i decided not to go back to honda.
I bought the OBD scanner on line and got the P0325 error and ended up on your solution page thanks to Google.
My car runs fine other than this minor error light but l will apply your solution when l buy the part required .
In the meantime wanted to thank you for being a resource to average people like myself.
Hi Ali
Thanks very much, I’m really pleased to hear it was helpful for you.
Best wishes
Andrew
Hi Andrew,
Very well presented information.
I had the same problem as described by you with my Honda CRV 2004. When speeding at 60 mph the Check Engine Light comes on, driving locally light goes out. Mechanic diagnosed Knock Sensor, bought a new one got it installed deleted P0325 now the light stays on even in town running. I have changed oil, oil filter and Plugs. OBD still reads Knock Sensor.
Please advise, Thanks.
Hi Tuani
Difficult to comment without seeing your car, but a few things to consider:
Best wishes
Andrew
Iv been having this problem also
Knock sensor replaced I drove 200meter and light came back on. Took it straight back to garage.
Same error code as before I believe it says unable to read knock sensor 1.however when the machine is still plugged in. The garage go onto a screen showing the knock sensor and it is reading it but code says it isn’t???? My garage are lost as to why they have had a check of wiring and can’t see any obvious problems. Taking about sending it to a electrics expert.
Car runs great tho
Thank You, Very well explain,I will try this myself..
Great, I hope it goes well!
Andrew
Hello Andrew I have a 2004 Honda CRV, would you be able to tell which part number for the knock sensor subwire? Many thanks
Hi Carlo
Sorry I can’t help with that part number. The parts diagrams I’ve got don’t seem to identify it separately.
Could the existing one be repaired or are the connectors broken? If you need the part number because you want to buy the part, then a Honda dealer will be able to help. If you want the part number to check equivalent parts, I doubt you’ll find an aftermarket version of that wire.
Hope you manage to get it sorted.
Thanks
Andrew
I had mine fixed at my Honda dealer cost £270 all in. I would have done it myself if I had been younger, being over 70 restricts getting up and down.
Thank you Andrew for this great write up and post. I have a 2005 Honda Element which is equipped with a K24. My issue has been intermittent with the light coming on under inconsistent situations.
Before making any assumptions, I felt it best to do some research. Thanks to your helpful post, this has been very enriching. Should the code come back, I now have a better idea how to problem solve the issue. Thank you!
very well explained thank you for your information
Thanks bro. it was useful information.
Sor how much is the cost of honda crv knock sensor 2003 model
Somewhere between £85 and £120 depending on where you buy it.
Click the link to search on ebay:
genuine Honda CR-V knock sensor on ebay
Cheers
Andrew
check your Tyre pressure [this is one solution ]
this happen to me when i put more air in my tires to save money for petrol 🙂
soon after the light come on ! because to much jumping give a shock to the engain
by thinking ” i reduce tyre pressure and it went off
Interesting angle on fixing the issue John! Cheers!
Hi thanks for great explanation!
Would you happen to have a good and easy explanation to find an intake air system leak.
Ernie, sounds like you need a smoke machine!
Here is a video showing a smoke machine in use (on a Toyota but you get the idea).
i had the same problem on my honda acord 2003 replaced knock sensor still came back on so my m the auto electrician said its easyer to replace the engine because the because the knock sensor is detecting a knock in the engine thats y it comes on so i did and put all the parts knock sensor the lot of the old engine and ive never had a problem since
Interesting story, thanks for sharing.
Cheers
Andrew
Hi! I had the same P0325 code as well and was dreading fixing it but I read thru your page and wacked it out in 25min. Thanks!
Great, glad it worked for you.
My mechanic replaced the knock sensor on my 2004 Honda CR-V with P0325 code. The same code returned.May using an OEM Honda sensor instead of the aftermarket sensor he used fix the problem?
Yes it might fix it. I’ve heard of other people having a similar experience to that, including one of the other commenters on this very post. Hope you manage to get it sorted out.
Great article. I had the P0325 fault come up. Money was very tight, after looking at the OEM part an its price, bought a replacement ‘new’ knock sensor from eBay for around £13 just to see if that was the problem (rather than throw over £100 on a Honda part, only for that not to cure the problem). Reset the code, ran the engine, and light came on when it had warmed up! Bought another one from EuroCarParts, made by ERA, £65 this time. Changed it again, but again, light came back on when warmed up. I connected the original knock sensor to an oscilloscope (on the bench) and struck it lightly with a metal spanner. The waveform was quite reasonable, but not exactly the shape I would have expected. I then did the same with the eBay part, and the output was rubbish! No wonder it didn’t fix the fault. So, I bit the bullet and bought a new Honda part. Before fitting it, I wired it up to the oscilloscope and got a waveform similar to the faulty removed device, but it was a cleaner waveform. Fitted the part…..no fault!!!! Should have just fitted Honda in the first place! Also, just to add. When I removed the ERA part I also attached it up to the scope. Waveform was very similar to the eBay part….. RUBBISH! Obviously that will get taken back an thrown at them!
Hi Nik, thanks for taking the time to share your experience. I’m glad the Honda part fixed it – interesting to read your research on the different waveforms. Glad the extra expense is worth it – I certainly winced when they told me the price for a genuine knock sensor! Cheers, Andrew
Very informative. Thank you.
Great, glad you liked it.
This page was very helpful. Easily managed to change the knock sensor on my 04 CRV.
Thanks Andrew
Great to hear, glad you liked it.
Hi Andrew – great review – do you know where the sensor would be on a 2003 stream? Same place
Thanks! I think the Stream was available with a 1.7 litre D17 engine and the 2 litre K20. So if it’s the 2 litre engine I’m pretty sure the sensor will be in the same place as on the CR-V in this article. If it’s the 1.7, then I’m not sure where it will be, but it will most likely be threaded directly into the block as per this article.
I too had the error with my Honda CRV and it was down to low tyre pressure.
How did your car run during the time of the failure ? Did you notice a difference in the car’s performance?
At the time I thought it was running ok, but once I replaced the sensor I realised it had been running a little rough. In particular there was a slight hesitation when accelerating.
I learned a lot by reading your article. We were quoted $350 to replace but will try to replace on our own! Great job of thoroughly explaining symptoms and repair
Thanks very much for the feedback Mark, I hope you manage(d) to get it fixed.
I have the same problem! I bought a 2003 Honda CRV a few weeks ago. And I had a engine management light up on my dash so I scanned the vehicle and it came up with Knock sensor code and also a DTC code which was the Electric load detector. I’ve replaced the knock sensor and also the ELD but the ELD code is no longer there but the knock sensor code keeps coming back up. I ordered the knock sensor from a local motor factors and it cost me around £60.
Sorry to hear it Richard. The first thing I would do is check the integrity of the wiring to the knock sensor. If that’s all OK, the next thing may be to get a genuine Honda knock sensor. Someone else who has commented on this post has had a similar problem to you, where an aftermarket knock sensor didn’t fix the problem.
Cheers
Andrew
please andrew i have a knock sensor problem i have a 2005 civic s 2ltr i have had two knock sensors fitted i was told to get a honda knock sensor the silver one but i cant find any detail about civic 2005 knock sensor please can you help it keeps telling me to get crv knock sensor
Hi John, if you’ve decided to get the genuine Honda sensor, then why not order it from your local Honda dealership. This will ensure you get the right one for your car.
I hope you manage to get it fixed.
Hi andrew,
My honda crv 2002 are getting the code same as you..there is no light engine (p0325) when started the engine and take a drive until reach 3000rpm the light will come up..then switch off the engine..started again no light..reach 3000rpm light come up..is that possible the knock sensor?
It could be, have you checked for history codes (rather than current codes) in the ECU?
Very well explained well done
Thanks!
Hi Andrew. I have a 2003 V.Tec CRV. and have a knock sensor code. On U tube and checking with Honda they say that the sensor is at the rear of the block, and I have found a sensor just above the oil filter which has a small nut keeping the cable on to the ellement rather than the black plastic push on. So is the knock sensor on the front or at the back? and what would this other sensor be please.
Hi Andrew. I sent you a message yesterday regarding my 2003 I VTEC CRV but I cant see it now. Did you not receive it or has it been taken down.
Hi Don
I’ve replied by email, haven’t heard anything back from you yet.
Andrew
So, my issue is with the knock sensor with my 2012 ridgeline. I’ve had the sensor and the harness changed twice. One by my personal mechanic and the second time by the dealership. Frustrated!!
If they used genuine components then that points to a problem elsewhere. Perhaps with the connection to the ECU?