P0497: EVAP System Low Purge Flow
Key takeaways
- P0497 means the engine computer commanded the purge valve open but saw little or no vacuum or flow come through from the EVAP system.
- It's an emissions code: the car is safe to drive, but it will fail an emissions or plug-in inspection.
- A purge valve stuck shut, a cracked, collapsed or disconnected purge hose and a wiring fault at the valve are the usual causes.
- GM has preliminary information for the 2011–2014 Chevrolet Volt and 2014–2016 Cadillac ELR telling technicians to replace any EVAP part saturated with liquid fuel when P0497 sets.
- Most P0497 repairs at a US independent shop run $100–$350; a clogged charcoal canister is the expensive outcome at $300–$800.
What P0497 means
The engine isn’t pulling in as much fuel vapor from the EVAP system as it should when the computer asks for it.
Scanners call it Evaporative Emission System Low Purge Flow. The EVAP system stores fuel vapor in a charcoal canister, and a purge valve lets engine vacuum draw that vapor in to be burned. During its self-test, the engine computer opens the purge valve and watches the fuel tank pressure sensor for vacuum, or on some cars watches fuel trims shift as vapor arrives. If little or no change shows up, it sets P0497. It’s the mirror image of P0496, where vapor flows when it shouldn’t.
Is it safe to drive?
Yes. The car runs normally, and most drivers only notice the light. P0497 is an emissions fault, and the car will fail an emissions or plug-in inspection until it’s fixed.
What changes the answer: a strong raw-fuel smell around the car or a visible fuel leak. Vapor that can’t be purged builds up in the canister, but liquid fuel on the ground is a fire risk; park it. If the pump nozzle keeps clicking off early, the canister may be saturated; get it looked at soon.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Purge valve stuck shut or clogged | Commanded on with a scan tool, it clicks but passes no vacuum; charcoal or debris inside | $120–$350 |
| Cracked, collapsed or disconnected purge hose | Look along the line from the valve to the intake; smoke test finds hidden cracks; on turbo engines check the in-line check valves | $100–$300 |
| Wiring or connector at the purge valve | No power or no control signal at the plug with the valve commanded on | $100–$250 |
| Software calibration or a model-specific procedure | A manufacturer bulletin matches your car and code | Often $0 under warranty; $100–$200 otherwise |
| Faulty fuel tank pressure sensor | Reading doesn’t move while purge is commanded, but vacuum is present at the valve | $150–$400 |
| Charcoal canister clogged or soaked with liquid fuel | Charcoal or fuel in the lines or valve; history of topping off; dusty-road driving | $300–$800 |
What to check first
- Read every stored code. P0497 with a purge valve circuit code points to wiring. With leak codes, a cracked hose is likely.
- Test the purge valve. A shop can command it on and off while watching tank pressure. With the engine idling and the valve commanded open, there should be vacuum at the canister side.
- Walk the purge hose. It runs from the canister to the intake, near hot parts. Look for a hose that’s cracked, collapsed, melted or knocked off after other work.
- Check for a bulletin. GM has issued preliminary information for the 2011–2014 Chevrolet Volt, 2014–2016 Cadillac ELR and the related Opel Ampera: inspect every EVAP part, replace anything saturated with liquid fuel, blow out the lines, and warn the owner that overfilling the tank can bring it back. Land Rover has a bulletin for 2013–2014 LR4 and Range Rover models with the 5.0L engine that ties P0497 and other purge codes to the purge valve.
- Look for charcoal. Black grains in the valve or lines mean the canister is breaking down and will ruin a new valve.
- Clear it and drive. EVAP tests need several drive cycles, often with the tank between a quarter and three-quarters full. If the light stays off for a week, the repair worked.
Our guide on how to read check engine light codes explains how EVAP codes fit with the rest of a scan.
What it costs
The cheap outcome is a connector repair or a hose, $100–$300, or a software fix that’s free under warranty. The common outcome is a purge valve at $120–$350. The expensive outcome is a charcoal canister at $300–$800, when it’s soaked with fuel from overfilling, charcoal has broken loose or dirt has packed it. Stop at the first click at the pump so it doesn’t happen again. A quick purge valve command test is the cheapest diagnosis you’ll get for this code. If you want help reading the results, ask our AI mechanic.
Related codes
P0496 (high purge flow) and P0441 (incorrect purge flow) are the same purge system seen from other angles. A leaking purge hose can also cause a lean code like P0171. With P0455 or P0451 on the same scan, look for a shared hose, connector or software cause. For the general question, see can I drive with the check engine light on.
What owners report to NHTSA
3 complaints filed with NHTSA mention P0497, 3 of them since 2015, across 2 different models. The component owners most often filed it under: engine.
Manufacturer service bulletins that name P0497
8 technical service bulletins and manufacturer communications filed with NHTSA mention P0497, from 4 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- CADILLAC ELR (2014, 2015, 2016), bulletin 10114679: This Preliminary Information communication provides information to the technician about vehicles that have a Service Engine Soon Malfunction Indicator Lamp on. Technician may find Diagnostic Trouble Code P0497 stored. Te…
- CHEVROLET VOLT (2011, 2012, 2013, 2014), bulletin 10114679: This Preliminary Information communication provides information to the technician about vehicles that have a Service Engine Soon Malfunction Indicator Lamp on. Technician may find Diagnostic Trouble Code P0497 stored. Te…
- LAND ROVER LR4 (2013, 2014), bulletin 10101325: "ISSUE: CHECK ENGINE LIGHT ILLUMINATED. DTC(S) RELEVANT TO A PURGE VALVE CONCERN STORED IN THE PCM. DTCS BELOW COULD POTENTIALLY INDICATE A CONCERN WITH THE PURGE VALVE. P0442 - SMALL LEAK P0444 - PURGE VALVE CIRCUIT OPE…
- OPEL AMPERA (2012, 2013, 2014), bulletin 10160649: This Preliminary Information communication provides information to the technician about vehicles that have a Service Engine Soon Malfunction Indicator Lamp on. Technician may find Diagnostic Trouble Code P0497 stored. Te…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
What is the difference between P0496 and P0497?
They are opposite faults on the same purge system. P0496 means vapor flows when the purge valve should be shut, usually a valve stuck open. P0497 means too little flows when the valve is open, usually a valve stuck shut or a hose that isn't carrying vacuum.
Can I drive with P0497?
Yes. The engine runs normally. Vapor that can't be purged stays in the canister, so over time you may smell fuel near the car or see the pump nozzle click off early. Fix it before the canister gets saturated.
Can a gas cap cause P0497?
Not usually. A loose cap lets outside air in, which can make vacuum hard to build during the test, but it more often sets leak codes like P0455. Tighten it until it clicks and look at the purge valve and hoses next.
Can I clean a purge valve instead of replacing it?
Sometimes a valve stuck with debris frees up, but charcoal grains from the canister usually come back. On most cars a new valve is the better repair, and if you find charcoal in it, the canister needs a look too.