Open circuit or high resistance in the monitor circuit wiring or connector (corrosion, chafing, pin damage); Faulty secondary air system monitor sensor or switch, or its vacuum or pressure supply; Short to voltage on the monitor signal wire; Secondary air pump, relay or control valve not operating, so the monitor reads incorrectly; Blocked, split or disconnected secondary air hoses or check valve faults; Faulty PCM or its reference voltage supply.

P1442

Secondary Air Injection System Monitor Circuit High Voltage.

Mercury
Powertrain
Manufacturer code
Low severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
4: AreaAuxiliary emission controls
42: FaultThe specific fault in that area

What it means

On Mercury models, P1442 means the engine control unit (PCM) saw a high voltage on the secondary air injection system monitor circuit. The monitor circuit reports whether the secondary air system is working, so the PCM sets the code when the signal sits above its expected range. Layout and components vary by model and engine, so check the manufacturer's wiring information for the vehicle in question.

Symptoms

Check engine light on
Possible failed emissions test or monitor not completing
Rattling, whining or no noise from the secondary air pump at cold start
Slightly higher cold-start emissions or rough cold idle on some engines
Usually no noticeable change in driveability

Possible causes

Open circuit or high resistance in the monitor circuit wiring or connector (corrosion, chafing, pin damage)likely
Faulty secondary air system monitor sensor or switch, or its vacuum or pressure supplylikely
Short to voltage on the monitor signal wirepossible
Secondary air pump, relay or control valve not operating, so the monitor reads incorrectlypossible
Blocked, split or disconnected secondary air hoses or check valve faultspossible
Faulty PCM or its reference voltage supplyrare

How to diagnose

Read stored codes and freeze frame data, noting any other secondary air or related codes, then check for applicable service bulletins for the model
Visually inspect the secondary air pump, relay, fuses, hoses, valves and the monitor circuit wiring and connectors for damage, corrosion, water or heat damage
Check the secondary air system fuse and relay and confirm correct power and earth supply to the pump
Check the monitor sensor or switch connector and measure its signal and reference voltage against the manufacturer's specification
Check the signal wire for open circuit, high resistance or short to voltage with the connector unplugged at both ends
Use a scan tool to command the secondary air pump and valve on and watch the monitor signal respond
Inspect hoses and check valves for blockages, cracks or exhaust moisture damage, and check any vacuum supply to the valve
If all wiring and components test correctly, check the PCM supply and grounds before considering a fault in the PCM

How to fix

Repair or replace damaged wiring, terminals or connectors in the monitor circuit
Replace the faulty monitor sensor or switch
Replace a failed secondary air pump, relay, fuse or control valve as confirmed by testing
Replace blocked, split or perished hoses and faulty check valves
Replace or repair the PCM, or update its calibration only where a known fault is documented, as a last resort after all other tests

Can I keep driving?

Low severity

The car can normally be driven as the fault mainly affects cold-start emissions monitoring. Book it in soon so the check engine light does not mask other faults and to pass an emissions test.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.