What does code P0440 mean on a Cadillac and is it safe to drive?
P0440: Evaporative Emission System Control System Malfunction. Here's what it means on your Cadillac, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
PowertrainLow urgency
What this code means
A general fault in the EVAP system—could be a leak, stuck valve, or sensor issue.
Common causes for your Cadillac
- Gas cap loose or faulty
- Purge or vent valve stuck
- Charcoal canister or hose leak
Symptoms
- Check Engine Light
Typical fixes
- Replace gas cap
- Test purge/vent valves
- Smoke test EVAP system
Repair cost range
For a Cadillac, repairs for P0440 often fall between $20 and $400, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Cadillac
Cadillac P0440 on older Northstar 4.6L and 4.9L platforms—gas cap first, then EVAP purge valve. On DeVille and DTS, the EVAP canister is under the trunk area and can crack with age; inspect it physically.
Most commonly affected models
DeVille 2001–2005DTS 2006–2011STS V8 2005–2011