Summary: The original TPMS sensors in a 2004-2006 MDX will probably need replacing soon. You can use aftermarket TPMS sensors to save a bundle of money, but you may need to clear the codes in the TPMS computer.
Background: The Tire Pressure Monitoring System (TPMS) became standard equipment on all MDXs beginning with the 2004 model year. TPMS operates based on signals provided by TPMS sensors mounted inside each of the four tires. Inside each TPMS sensor is a non-replaceable battery which powers that signal.
The original part number for the TPMS sensor for a 2004-2006 MDX was 06421-S3V-A00, which had a list price around $30 each. This part has been discontinued, and has been superseded by the replacement part number 06421-S3V-A04, which has a list price around $100 each.
So here's my story. I have a 2004 MDX. Last fall, the TPMS warning light on the dash - the one that says TPMS - came on, and was on most of the time. At that time, I was using my original wheels with their original, twelve-year-old TPMS sensors. I knew about the non-replaceable batteries in them, so I assumed that the warning light was probably caused by the failure of those batteries. At the start of winter, I swapped to my winter tires, which were mounted on wheels along with TPMS sensors that I bought in September 2011, and the TPMS warning light went out, thereby confirming my assumption that the original sensors needed replacing. Later on in winter, I switched back to my original wheels and TPMS sensors, and the TPMS light once again appeared. Because the original part number TPMS sensors are no longer available and I didn't want to pay triple the price for the replacement ones I bought aftermarket replacement sensors. The ones I bought are made by Dorman, their part number 974-037. I bought a set of four from Direct Auto for $98 with free shipping. (A quick check on Autozone's website shows sensors made by Schrader, VDO, and Wells, at prices from $45 to $60 each.)
When my (independent) mechanic installed the new aftermarket TPMS sensors on the car, he mentioned that the TPMS warning light was still on, and asked me if there was a learning cycle for it. I knew that there was, that you need to take a short drive when changing the TPMS sensors, and then the warning light should go out. (The spec in the service manual says you need to drive at least 15 mph for at least 40 seconds.) So I told him not to worry about the warning light, and I picked up the car.
However, the TPMS warning light did not go out, even after driving 40+ miles on it. Although now it was slightly different; when starting out, it would show the other TPMS warning light (the little icon that looks like the cross-section of a tire, with an exclamation point in the middle) for a few miles, then switch to the warning light that has the word TPMS.
I contacted Dorman technical support using the chat function on their website, to ask them if they had any advice. They said it was possible that their TPMS sensors were asleep (their terminology), and that I should try removing the valve cores from the valve stem part of the TPMS sensors for 3-5 seconds and then re-inflate, that the sudden drop in pressure might wake up the TPMS sensors. I tried this, but the warning lights were still on after doing so.
At this point I was guessing that the aftermarket TPMS sensors wouldn't work, and I would need to buy Acura branded ones at the dealer. Fortunately, this guess turned out to be wrong. I took my car to the Acura dealer and explained the situation to them, asking them to do whatever diagnostics they could using the aftermarket sensors (without spending too much time going down that road) and then replace them if necessary. They found that the TPMS computer had set a whole bunch of error codes. They cleared the codes and tried taking it for a short drive, without changing the TPMS sensors yet. Lo and behold, the TPMS warning light did not come back on, and has not come on since then. Problem solved! So I only had to pay a nominal diagnostic charge, and did not have to buy Acura-branded sensors for several hundred dollars.
With the benefit of hindsight, I erred in telling my independent mechanic who installed the sensors not to worry about the warning light, and should have instead told him to clear the codes. But now I know that, and I'll tell him that six years from now when we have to replace the TPMS sensors in my winter wheels, which will then be twelve years old and need replacing.
I hope retelling this story benefits other owners who are not sure what to do when the batteries in their original TPMS sensors wear out. Inexpensive aftermarket ones appear to work fine... but you may need to clear the codes in the TPMS computer to make the dash warning light go out.
Background: The Tire Pressure Monitoring System (TPMS) became standard equipment on all MDXs beginning with the 2004 model year. TPMS operates based on signals provided by TPMS sensors mounted inside each of the four tires. Inside each TPMS sensor is a non-replaceable battery which powers that signal.
The original part number for the TPMS sensor for a 2004-2006 MDX was 06421-S3V-A00, which had a list price around $30 each. This part has been discontinued, and has been superseded by the replacement part number 06421-S3V-A04, which has a list price around $100 each.
So here's my story. I have a 2004 MDX. Last fall, the TPMS warning light on the dash - the one that says TPMS - came on, and was on most of the time. At that time, I was using my original wheels with their original, twelve-year-old TPMS sensors. I knew about the non-replaceable batteries in them, so I assumed that the warning light was probably caused by the failure of those batteries. At the start of winter, I swapped to my winter tires, which were mounted on wheels along with TPMS sensors that I bought in September 2011, and the TPMS warning light went out, thereby confirming my assumption that the original sensors needed replacing. Later on in winter, I switched back to my original wheels and TPMS sensors, and the TPMS light once again appeared. Because the original part number TPMS sensors are no longer available and I didn't want to pay triple the price for the replacement ones
I bought aftermarket replacement sensors. The ones I bought are made by Dorman, their part number 974-037. I bought a set of four from Direct Auto for $98 with free shipping. (A quick check on Autozone's website shows sensors made by Schrader, VDO, and Wells, at prices from $45 to $60 each.)When my (independent) mechanic installed the new aftermarket TPMS sensors on the car, he mentioned that the TPMS warning light was still on, and asked me if there was a learning cycle for it. I knew that there was, that you need to take a short drive when changing the TPMS sensors, and then the warning light should go out. (The spec in the service manual says you need to drive at least 15 mph for at least 40 seconds.) So I told him not to worry about the warning light, and I picked up the car.
However, the TPMS warning light did not go out, even after driving 40+ miles on it. Although now it was slightly different; when starting out, it would show the other TPMS warning light (the little icon that looks like the cross-section of a tire, with an exclamation point in the middle) for a few miles, then switch to the warning light that has the word TPMS.
I contacted Dorman technical support using the chat function on their website, to ask them if they had any advice. They said it was possible that their TPMS sensors were asleep (their terminology), and that I should try removing the valve cores from the valve stem part of the TPMS sensors for 3-5 seconds and then re-inflate, that the sudden drop in pressure might wake up the TPMS sensors. I tried this, but the warning lights were still on after doing so.
At this point I was guessing that the aftermarket TPMS sensors wouldn't work, and I would need to buy Acura branded ones at the dealer. Fortunately, this guess turned out to be wrong. I took my car to the Acura dealer and explained the situation to them, asking them to do whatever diagnostics they could using the aftermarket sensors (without spending too much time going down that road) and then replace them if necessary. They found that the TPMS computer had set a whole bunch of error codes. They cleared the codes and tried taking it for a short drive, without changing the TPMS sensors yet. Lo and behold, the TPMS warning light did not come back on, and has not come on since then. Problem solved! So I only had to pay a nominal diagnostic charge, and did not have to buy Acura-branded sensors for several hundred dollars.
With the benefit of hindsight, I erred in telling my independent mechanic who installed the sensors not to worry about the warning light, and should have instead told him to clear the codes. But now I know that, and I'll tell him that six years from now when we have to replace the TPMS sensors in my winter wheels, which will then be twelve years old and need replacing.
I hope retelling this story benefits other owners who are not sure what to do when the batteries in their original TPMS sensors wear out. Inexpensive aftermarket ones appear to work fine... but you may need to clear the codes in the TPMS computer to make the dash warning light go out.
