Faulty leak detection pump switch or the pump assembly itself.; Damaged, disconnected, or corroded wiring or connector at the LDP switch.; Failed leak detection pump (mechanical diaphragm or solenoid).; Restricted or disconnected EVAP hose between the LDP and the fuel tank.; Powertrain control module (PCM) internal driver fault, though rare.; A stuck-open or stuck-closed EVAP canister purge solenoid affecting system pressure.; A physical leak in the EVAP system that prevents the LDP from building pressure.

DTC codes / Chrysler codes / P1494

P1494 · ChryslerLeak Detection Pump Switch Or Mechanical Fault

Q: What does code P1494 mean?

Leak Detection Pump Switch Or Mechanical Fault. P1494 on Chrysler vehicles indicates that the leak detection pump (LDP) switch circuit is not responding as expected during the natural vacuum leak detection monitor. The powertrain control module (PCM) commands the LDP to pressurize the evaporative emission (EVAP) system and then looks for the switch to change state within a calibrated time; when it does not, the PCM stores this code.

P1494 on Chrysler vehicles indicates that the leak detection pump (LDP) switch circuit is not responding as expected during the natural vacuum leak detection monitor. The powertrain control module (PCM) commands the LDP to pressurize the evaporative emission (EVAP) system and then looks for the switch to change state within a calibrated time; when it does not, the PCM stores this code.

SystemPowertrain

Code typeChrysler specific

SeverityLow

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

Malfunction indicator lamp (MIL) illuminated, often with no other drivability symptoms.
Intermittent rough idle or slight hesitation after refueling, though this is uncommon.
A faint fuel odor may be present around the rear of the vehicle if the EVAP system has a physical leak.
Failed state emissions inspection due to the commanded MIL.
No noticeable change in engine performance or fuel economy in most cases.

Common causes, most likely first

Faulty leak detection pump switch or the pump assembly itself.
Damaged, disconnected, or corroded wiring or connector at the LDP switch.
Failed leak detection pump (mechanical diaphragm or solenoid).
Restricted or disconnected EVAP hose between the LDP and the fuel tank.
Powertrain control module (PCM) internal driver fault, though rare.
A stuck-open or stuck-closed EVAP canister purge solenoid affecting system pressure.
A physical leak in the EVAP system that prevents the LDP from building pressure.

How to diagnose and fix it

Connect a scan tool and verify that P1494 is active or pending, then check for any related EVAP codes.
Inspect the LDP electrical connector and harness for corrosion, loose pins, or chafed wires; repair as needed.
Command the LDP on and off with the scan tool and listen for the pump to run; if it does not, test the pump motor circuit.
Test the LDP switch signal circuit with a multimeter while commanding the pump; compare to manufacturer specifications.
Perform a smoke test on the EVAP system to rule out a physical leak that could prevent switch activation.
If the switch or pump fails electrical or mechanical testing, replace the leak detection pump assembly.
Clear the code and run the EVAP monitor to confirm the repair; verify no pending codes return.

LDP switch faults often misdiagnosed

A stuck-open or leaking EVAP purge solenoid can cause the LDP switch to not change state, leading to a false P1494 without any fault in the pump itself.
The LDP switch is a simple reed or pressure switch; testing it with a scan tool's bidirectional controls is far more reliable than static resistance checks.
Corroded terminals at the LDP connector are a common cause on older Chrysler vehicles, especially those driven in salt-belt states.
A physical EVAP leak large enough to prevent pressure buildup will set P1494 along with leak codes, so always smoke-test before replacing the pump.
The PCM expects the switch to toggle within a specific time window; a slow-responding pump due to a clogged filter can trigger P1494 without a hard failure.

Can I keep driving with P1494?

The vehicle remains safe to drive under normal conditions because P1494 does not affect engine operation or safety systems. Avoid topping off the fuel tank and schedule diagnosis soon to prevent a small EVAP leak from worsening.

Tools that help

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Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.