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1998 Dodge Caravan P0172 Code: Engine Dies at Idle, Stalls Below 500 RPM

Model: caravan Fault Code: P0172 Posted: 2010-07-06 08:49

My 1998 Dodge Caravan starts fine and runs smoothly above 15 mph, but when coming to a stop, it drops to around 500 RPM and begins to stall. It has died once while stationary this morning. The issue appears to start after the vehicle warms up during the first few miles of driving. A P0172 diagnostic code is now stored in the ECU, indicating an overly rich fuel mixture. I've already tried replacing the PCV valve and using a fuel system cleaner with no improvement. The engine runs fine at higher speeds but struggles to maintain a stable idle. I'm looking for cost-effective troubleshooting steps before replacing parts—any advice on what to check next?

Related fault codes
P0172
Comments (9)
Anonymous 2010-07-06 12:15

P0172 indicates an overly rich fuel mixture. What engine variant do you have? (e.g., 3.0L)?

Anonymous 2010-07-06 12:19

I have a 3.0L engine—corrected from 1000 RPM to 500 RPM for accuracy.

Anonymous 2010-07-06 12:31

Have you recently performed any maintenance, such as throttle body or fuel injector cleaning? These components require regular servicing to maintain a smooth idle. Professional cleaning using proper tools and cleaners is recommended—avoid fuel additives sold for tank use, as they are often too harsh and can damage sensitive fuel system parts.

Anonymous 2010-07-06 12:34

I haven’t done throttle body service in about two years. That’s what I plan to try next. What cleaner or method do you recommend? Could cleaning the throttle body help improve injector performance?

Anonymous 2010-07-06 20:09

I want to clarify—after over a decade at a Dodge dealership and nearly 15 years as an engine technician, I’ve never seen a dirty throttle body cause P0172. In fact, 90% of the P0172 codes I've encountered on 1998 Caravans are due to either a stuck oxygen sensor or an EGR valve that remains open when it shouldn’t. Fuel system cleaning is not the solution—investigate these two components first.

Anonymous 2010-08-16 10:49

Jeff, I’d like your expert advice. My van now stalls as I slow down—it drops to 400 RPM and then tries to idle back up to 750. Sometimes it does, but often it just dies with a rough idle. Occasionally, I smell strong exhaust fumes. Should I prioritize checking the EGR valve or oxygen sensor?

Anonymous 2010-08-16 15:46

Does your vehicle still show only the P0172 code? If you want to test whether the EGR is at fault, remove it and install a factory-style EGR block-off gasket (e.g., made from a tin can) to stop exhaust flow. If idle improves, the EGR was likely stuck open. If no change, then the issue may lie with the oxygen sensor or another system component.

Anonymous 2010-08-16 19:40

Thanks! That’s exactly what my friend—a Chrysler engineer—recommended. I’m going to try this EGR block-off test this week. Appreciate your help!

Anonymous 2010-08-16 20:11

If an oxygen sensor replacement is needed, avoid Bosch units—they don’t perform as well in older vehicles. Opt for NTK or a dealer-grade sensor instead.