What does it mean?
P1437 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: EVAP Emission Control LDP Circuit Malfunction Pump Problem .
Symptoms
- MIL on with the EVAP readiness monitor never completing
- No pump sound during the leak test, which normally runs after the engine is switched off
- Other EVAP codes stored alongside, sometimes false leak codes
- Occasional fuel vapour smell if a genuine leak also goes undetected
- No change in drivability
Likely causes
- Failed leak detection pump motor or internal diaphragm
- Open or shorted wiring in the pump control or supply circuit
- Corroded connector at the pump, which is usually mounted low near the canister
- Blown fuse or failed relay supplying the pump
- Blocked pump filter or a vent line packed with dirt, so the pump cannot build pressure
- Water frozen inside the pump or its vent path in cold weather
- Poor ground for the pump assembly
How to fix it
- Command the leak detection pump with a scan tool and listen for it running
- Inspect the pump connector and harness under the vehicle for corrosion, water and road damage
- Check the fuse and relay feeding the pump, then verify battery voltage at the pump connector with the key on
- Measure the pump motor resistance and compare against specification
- Perform a voltage drop test on the pump ground
- Remove and inspect the pump filter and vent hose for dirt, insects and blockage
- Replace the leak detection pump when the supply, ground and control circuits are proven good, then rerun the EVAP monitor