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The Honda Civic GX has two coalescing filter elements. This is part two of a two part series that describes how to change the coalescent filters on the 2001, 2002, 2003, 2004, and 2005 Honda Civic GX. This post describes how to change the low pressure coalescent filter element. The low pressure filter is housed in a red self contained canister that is located under the front of the car almost directly above the oil filter. The filter looks exactly like a traditional oil filter. The low pressure filter is made for Honda by Toyo Roki of Thailand. The Honda part number of the filter is 16230-PMS-A03. This filter costs over a hundred dollars. To try and save money and make some money selling these filters I made several unsuccessful attempts to purchase these filters directly from Toyo Roki or one of their distributors. In researching this filter I found a patent description for the filter. The patent and the low demand accounts for the reason there are no off brand non-Honda filters available. A picture of the low pressure filter is attached to this post. For instructions on changing the high pressure filter element click here.
Disclaimers & Precautions: Working underneath vehicles is inherently dangerous and can result in serious injury and even death. Working with pressurized CNG is inherently dangerous and can result in serious injury and even death. Any and all of these procedures should be performed with the vehicle turned off and the keys removed from the ignition. In addition, follow any and all manufacture precautions specific to the vehicle on which you are performing work. Any work must take place on a flat level concrete surface in a well ventilated area away from open flames or ignition sources. Every appropriate precaution should be taken to safely secure the vehicle from moving. These precautions include, but are not limited to setting the emergency brake, placing an approved anti-rolling device on both sides of the all tires remaining on the ground. Never work under a vehicle that is suspended only by a jack. Use jack stands that are rated for the weight of the vehicle. Follow all manufacture instructions for any tools and equipment you use to complete this procedure. When working under a vehicle always wear safety glasses. If you do not understand these instructions, or feel unsure about working on cars do not perform this work yourself.
Procedure
***You will need an oil filter wrench specifically sized for the low pressure filter canister. Without an oil filter wrench that grips the bottom of the lower pressure filter canister very tight you will be unable to remove the filter. The filter is usually attached super tight because most mechanics do not oil the filter gasket and the rubber is stuck to the mating surface. The cap style filter wrench works well but you have to verify that the grip is super tight because they have a tendency to slip. I have included pictures of several types of filter wrenches.***
1. Turn off the emergency CNG shutoff valve located at the rear of the vehicle just behind the rear tire on the driver’s side. (See picture)
2. Depressurize the CNG lines by performing the following: With the emergency shutoff valve in the closed position, start the car and let idle, or accelerate the engine until the gas is used between the shut off valve and the engine. When this happens the engine will quit. This takes 2 min or less. If the car never runs out of gas and quits, repeat step 1. Verifying that the valve is completely closed. If after a second attempt the vehicle does not quit after a maximum of three minutes; take the vehicle to the Honda dealer to have the shut-off valve diagnosed or replaced. DO NOT attempt this procedure if you cannot depressurize the CNG system as described in steps 1. And 2.
3. After the car quits, remove the key from the ignition and set the emergency brake.
4. Secure both rear tires so the car cannot roll forward or backward
5. Use a jack to lift the front of the vehicle onto jack stands. Place the jack stands under the manufacture specified jacking locations on each side of the vehicle.
6. The low pressure filter is housed in a red self contained canister that is located under the front of the car almost directly above the oil filter. (See picture).
7. Use previously sized oil filter wrench attached to a long socket extension to remove the lower pressure coalescent filter canister. I included a picture of the filter wrench and socket extensions I used to remove the filter. The filter wrench I already had in the garage did not quite close tight enough. To compensate I had to put cut pieces of rubber tubing on the clamp teeth so the filter wrench had enough grip to loosen the filter. I had just changed the high pressure filter so there was no pressure in the CNG lines. If you were changing the low pressure filter independent of the high pressure filter and the CNG lines had not already been completely depressurized you will need to loosen the filter one and a half to two rotations until you here the CNG gas escaping. Wait until no more gas can be heard escaping from the canister. This should take no more than two minutes. Slowly finish removing the filter canister by hand.
8. Check to make sure the black rubber gasket is attached to the top of the used low pressure filter canister. If the gasket is missing, make sure it is not attached to the mating surface of the filter mount. Remove the gasket from the filter mount if still attached.
9. Use a clean dry rag to clean the filter threads and filter gasket mating surface.
10. Lubricate the gasket on the new low pressure filter with oil or light grease. This will ensure the filter is easy to remove next time.
11. Install the new lower pressure filter canister back into position by threading the canister clock wise. Tighten the canister ¾ to 1 complete rotation once the filter gasket first touches the mating surface. I was able to sufficiently tighten the filter using both hands. I was wearing mechanics gloves to give me extra grip. If you want to achieve more than hand tight, you will need a cap style filter wrench. The type of filter wrench I used is used for removal only.
12. Return the vehicle to the ground.
15. Turn on the emergency shut-off valve.
16. Done
Disclaimers & Precautions: Working underneath vehicles is inherently dangerous and can result in serious injury and even death. Working with pressurized CNG is inherently dangerous and can result in serious injury and even death. Any and all of these procedures should be performed with the vehicle turned off and the keys removed from the ignition. In addition, follow any and all manufacture precautions specific to the vehicle on which you are performing work. Any work must take place on a flat level concrete surface in a well ventilated area away from open flames or ignition sources. Every appropriate precaution should be taken to safely secure the vehicle from moving. These precautions include, but are not limited to setting the emergency brake, placing an approved anti-rolling device on both sides of the all tires remaining on the ground. Never work under a vehicle that is suspended only by a jack. Use jack stands that are rated for the weight of the vehicle. Follow all manufacture instructions for any tools and equipment you use to complete this procedure. When working under a vehicle always wear safety glasses. If you do not understand these instructions, or feel unsure about working on cars do not perform this work yourself.
Procedure
***You will need an oil filter wrench specifically sized for the low pressure filter canister. Without an oil filter wrench that grips the bottom of the lower pressure filter canister very tight you will be unable to remove the filter. The filter is usually attached super tight because most mechanics do not oil the filter gasket and the rubber is stuck to the mating surface. The cap style filter wrench works well but you have to verify that the grip is super tight because they have a tendency to slip. I have included pictures of several types of filter wrenches.***
1. Turn off the emergency CNG shutoff valve located at the rear of the vehicle just behind the rear tire on the driver’s side. (See picture)
2. Depressurize the CNG lines by performing the following: With the emergency shutoff valve in the closed position, start the car and let idle, or accelerate the engine until the gas is used between the shut off valve and the engine. When this happens the engine will quit. This takes 2 min or less. If the car never runs out of gas and quits, repeat step 1. Verifying that the valve is completely closed. If after a second attempt the vehicle does not quit after a maximum of three minutes; take the vehicle to the Honda dealer to have the shut-off valve diagnosed or replaced. DO NOT attempt this procedure if you cannot depressurize the CNG system as described in steps 1. And 2.
3. After the car quits, remove the key from the ignition and set the emergency brake.
4. Secure both rear tires so the car cannot roll forward or backward
5. Use a jack to lift the front of the vehicle onto jack stands. Place the jack stands under the manufacture specified jacking locations on each side of the vehicle.
6. The low pressure filter is housed in a red self contained canister that is located under the front of the car almost directly above the oil filter. (See picture).
7. Use previously sized oil filter wrench attached to a long socket extension to remove the lower pressure coalescent filter canister. I included a picture of the filter wrench and socket extensions I used to remove the filter. The filter wrench I already had in the garage did not quite close tight enough. To compensate I had to put cut pieces of rubber tubing on the clamp teeth so the filter wrench had enough grip to loosen the filter. I had just changed the high pressure filter so there was no pressure in the CNG lines. If you were changing the low pressure filter independent of the high pressure filter and the CNG lines had not already been completely depressurized you will need to loosen the filter one and a half to two rotations until you here the CNG gas escaping. Wait until no more gas can be heard escaping from the canister. This should take no more than two minutes. Slowly finish removing the filter canister by hand.
8. Check to make sure the black rubber gasket is attached to the top of the used low pressure filter canister. If the gasket is missing, make sure it is not attached to the mating surface of the filter mount. Remove the gasket from the filter mount if still attached.
9. Use a clean dry rag to clean the filter threads and filter gasket mating surface.
10. Lubricate the gasket on the new low pressure filter with oil or light grease. This will ensure the filter is easy to remove next time.
11. Install the new lower pressure filter canister back into position by threading the canister clock wise. Tighten the canister ¾ to 1 complete rotation once the filter gasket first touches the mating surface. I was able to sufficiently tighten the filter using both hands. I was wearing mechanics gloves to give me extra grip. If you want to achieve more than hand tight, you will need a cap style filter wrench. The type of filter wrench I used is used for removal only.
12. Return the vehicle to the ground.
15. Turn on the emergency shut-off valve.
16. Done
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