P1437 — Electric Air Pump Secondary Failure

For Ford vehicles

A/C evaporator air temperature circuit – signal too high

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P1437 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the electric air pump secondary for damage, corrosion, chafing or poor contact.
Subsystem check Measure reference voltage, ground and signal continuity at the component connector.
Subsystem check Wiggle-test the harness while watching the signal in live data — dropouts reveal broken wires.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P1437 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P1437 (parts and labor, USD, independent shop rates): Control module repair: $300–$1,000; Repair wiring or connectors: $80–$250; Replace the faulty sensor or actuator: $150–$500. Overall, fixing P1437 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How much does it cost to fix P1437?

Control module repair — $300–$1,000; Repair wiring or connectors — $80–$250; Replace the faulty sensor or actuator — $150–$500. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What is the most common cause of P1437?

The most common causes are: corroded, loose or damaged connector, poor ground connection, blown fuse feeding the circuit.

What does OBD2 code P1437 mean?

Electric Air Pump Secondary Failure (P1437): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by corroded, loose or damaged connector, poor ground connection, blown fuse feeding the circuit.

Is it safe to drive with P1437?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

Will P1437 clear itself?

Sometimes P1437 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

The secondary air injection system forces outside air into the exhaust manifold immediately after a cold engine start. This burst of fresh air raises oxygen levels in the exhaust, helping the catalytic converter heat up faster and burn off unburned hydrocarbons that occur during warm-up. On many vehicles, an electric air pump provides this secondary air supply. When the powertrain control module detects an electrical failure in the secondary (backup) pump circuit, it sets trouble code P1437.

This is not a code the ECU throws based on a single erratic reading. To prevent false alarms from temporary glitches, the module performs multiple verification cycles under defined operating conditions before it activates the check engine light and saves P1437 to memory. The freeze frame data stored alongside the code is a snapshot of critical engine parameters at the moment the fault was confirmed — engine load, RPM, coolant temperature, vehicle speed, and more. That data tells you precisely which driving conditions triggered the failure, making it the most reliable place to start when you want to reproduce the problem on a test drive.

Common Symptoms of P1437

The check engine light is illuminated and stays on.
The secondary air pump either does not run at all or operates inconsistently.
Depending on the vehicle, the engine may enter reduced-power limp mode.
Some drivers notice a drop in fuel economy because the engine compensates for the missing air injection.
A rough idle or hesitation under light load can occur in rare cases.
On-board emissions monitors may fail, preventing the vehicle from passing an emissions test.

What Causes P1437?

The most common root cause is damaged wiring or connectors in the secondary air pump circuit. Heat, vibration, and road debris gradually break down wire insulation and corrode electrical contacts, leading to open circuits or shorts that the ECU detects.

Blown fuse feeding the secondary air pump circuit
Chafed, broken, or melted wiring in the harness
Corroded, loose, or physically damaged electrical connectors
Faulty secondary air pump motor or its control solenoid
Poor ground connection at the pump or control module
Failed driver circuit inside the powertrain control module

How to Diagnose P1437

Hook up an OBD2 scanner and confirm that P1437 is stored. Save the freeze frame data immediately — it shows exactly what engine conditions were present when the fault was verified, which you will need to recreate during your road test.
Pull any other stored codes and note their relationship to P1437. Before diving into wiring tests, check whether the manufacturer has issued a technical service bulletin for this code on your specific model — some failures have documented software updates or known fixes.
Visually inspect the wiring harness and all connectors tied to the secondary air pump circuit. Look for frayed wires, melted insulation, corrosion on the pins, and any connectors that are not fully seated.
With the connector unplugged, check reference voltage, ground integrity, and signal continuity at the pump side of the harness using a multimeter. Compare your readings to what the manufacturer specifies.
Perform a wiggle test on the harness while monitoring live data on the scanner. Any signal dropouts or sudden value changes point to broken strands inside a wire that is still intact enough to carry a signal.
Clear the code and complete a full drive cycle under the exact conditions captured in the freeze frame. If P1437 returns, the fault is confirmed and you can proceed with the appropriate repair.

Repair Options and Costs for P1437

Address the least expensive likely causes before spending money on major components:

Repair wiring or connectors — $80–$250
Replace the faulty sensor, solenoid, or secondary air pump assembly — $150–$500
Control module repair or replacement — $300–$1,000

Total repair cost for P1437 typically falls between $80 and $1,000 depending on which part failed. Spending time on a thorough diagnosis first prevents buying an expensive control module when the problem turns out to be a loose ground wire or a blown fuse.

Can You Drive with P1437?

In most cases the vehicle remains drivable, though the secondary air injection system will not function, which means slightly higher emissions and a possible reduction in fuel economy. Severe symptoms such as stalling, hard starting, or unusual brake or steering behavior would make the situation urgent and justify immediate attention. Otherwise, schedule the repair at your earliest convenience — do not ignore the check engine light indefinitely.