P0452: EVAP System Pressure Sensor/Switch Low Input
Key takeaways
- P0452 means the fuel tank pressure sensor's signal dropped below the range the engine computer accepts.
- It's an emissions code: the car is safe to drive, but it will fail an emissions or plug-in inspection.
- Wiring and connector faults, a failed sensor, and a purge valve stuck open that pulls the tank into vacuum are the usual causes.
- Chrysler-group makes have bulletins for PCM software and kinked or misassembled purge lines, and Mazda has one for the CX-5 setting P0452 at startup.
- Most P0452 repairs at a US independent shop run $100–$400; a tank pressure sensor that needs the tank lowered costs more.
What P0452 means
The sensor that measures pressure in your fuel tank is sending a signal that’s too low.
Scanners call it Evaporative Emission System Pressure Sensor/Switch Low Input. The EVAP system traps fuel vapor from the tank in a charcoal canister and later burns it in the engine. To test that system for leaks, the computer seals it and watches the fuel tank pressure sensor. The sensor gets a 5-volt reference and returns a voltage that follows tank pressure. P0452 sets when that voltage sits below the range the computer expects. Usually that’s an electrical fault, but sometimes the tank really is under strong vacuum.
Is it safe to drive?
Yes. P0452 affects emissions monitoring, not how the engine runs. You will fail an emissions or plug-in inspection, and while the light is on for this, a second fault won’t get your attention.
What changes the answer: a strong raw-fuel smell or fuel dripping under the car. A liquid leak is a fire risk, not an emissions issue; park it and see what a gas smell means. A rough idle or hard start right after filling up points to a purge valve stuck open; get that checked within the week.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Wiring or connector at the sensor | Signal low or zero on a scan tool; damaged, corroded or loose plug on the tank or canister | $100–$250 |
| Failed fuel tank pressure sensor | Reference and ground good, but the reading stays low with the cap off | $150–$400; more when the tank has to come down |
| Software calibration on specific models | A manufacturer bulletin matches your car and code | Often $0 under warranty; $100–$200 otherwise |
| Purge valve stuck open, pulling the tank into vacuum | Reading jumps back to normal when the cap comes off; valve holds no vacuum when unpowered | $120–$350 |
| Kinked or misassembled purge or vent line | Bulletin for your model; visual check of the lines | $100–$300 |
| Shorted 5-volt reference shared with another sensor | Other sensor codes set at the same time; reference voltage low | $100–$250 |
What to check first
- Read every stored code. P0452 with other sensor codes points to a shared reference circuit. P0452 with P0496 points to a stuck-open purge valve.
- Look at the key-on reading with the cap off. A good sensor reads close to zero. If the reading is pinned at the bottom, it’s electrical; if it rises to zero when the cap comes off, the tank really was in vacuum.
- Check for a bulletin before buying parts. The pattern: Chrysler-group makes (Jeep, Ram, Dodge, Chrysler, Fiat) have PCM software updates and bulletins for a kinked purge line on the 2020 Charger, Challenger and 300 and a misassembled purge tube on the 2021–2022 Grand Cherokee. Mazda has a bulletin for 2013–2015 CX-5s that set P0452 or P0453 right after startup, Subaru changed an engine harness on the 2012–2014 WRX, and Ford covers the 2012–2015 Focus.
- Inspect the sensor connector and harness. The sensor sits on top of the tank or near the canister, where road water gets in.
- Clear it and drive. If it was a one-off, the light stays off after a few drive cycles.
What it costs
The cheap outcome is a connector repair or software update, from free under warranty to $100–$250. The common outcome is a new tank pressure sensor at $150–$400, more if the tank has to come down. A stuck purge valve at $120–$350 is the other common fix. Watching the sensor reading with the cap on and off tells you which one you have before you pay for parts. If you’re unsure where to start, ask our AI mechanic with your car and code list.
Related codes
P0451 is the same sensor reading implausibly and P0453 is it reading too high. P0452 with leak codes like P0455 or P0456 usually means the sensor needs testing before the leak search. If the light keeps coming on and going off, that fits a connector that gets wet.
What owners report to NHTSA
12 complaints filed with NHTSA mention P0452, 10 of them since 2015, across 10 different models. The component owners most often filed it under: fuel/propulsion system.
Manufacturer service bulletins that name P0452
45 technical service bulletins and manufacturer communications filed with NHTSA mention P0452, from 8 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- JEEP GRAND CHEROKEE (2021, 2022), bulletin 10212427: Incorrectly Assembled Purge Flow Tube Inside Tube Elbow This bulletin involves inspecting and if needed reposition the purge tube inside the tube elbow. Customers may experience a Malfunction Indicator Lamp (MIL) illumin…
- RAM PROMASTER CITY (2021), bulletin 10214617: Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further inves…
- DODGE CHARGER (2020), bulletin 10184466: Evaporative Emission Control System (EVAP) Purge Line Kinked This bulletin involves inspecting and possibly replacing the EVAP purge valve assembly. Customers may experience a Malfunction Indicator Lamp (MIL) illuminatio…
- CHRYSLER 300 (2020), bulletin 10184466: Evaporative Emission Control System (EVAP) Purge Line Kinked This bulletin involves inspecting and possibly replacing the EVAP purge valve assembly. Customers may experience a Malfunction Indicator Lamp (MIL) illuminatio…
- DODGE CHALLENGER (2020), bulletin 10184766: Evaporative Emission Control System (EVAP) Purge Line Kinked This bulletin involves inspecting and possibly replacing the EVAP purge valve assembly. Customers may experience a Malfunction Indicator Lamp (MIL) illuminatio…
- FIAT 500X (2016), bulletin 10121715: Flash: Diagnostic And System ImprovementsThis bulletin involves updating the Body Control Module (BCM), Powertrain Control Module (PCM) and Transmission Control Module (TCM) with the latest available software. All three …
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
Can a loose gas cap cause P0452?
Rarely. P0452 is about the sensor signal reading too low, which is usually electrical. A loose cap tends to set leak codes like P0455 or P0456 instead. Tightening it costs nothing, but expect to look at the sensor and wiring next.
Is P0452 always a bad fuel tank pressure sensor?
No. A broken signal wire, a corroded connector or a shorted 5-volt reference gives the same low reading. A purge valve stuck open can also pull real vacuum on the tank. Test the wiring and watch the reading with the cap off before buying the sensor.
Can I drive with a P0452 code?
Yes. The car runs normally. If you also get a rough idle or a hard start right after filling up, the purge valve may be stuck open; have that checked within the week.
Will P0452 go away on its own?
It can, if a connector got wet or a wire only shorts now and then. If it keeps coming back, the circuit or the sensor needs to be tested.