Understanding the P1405 Engine Trouble Code

The P1405 is a manufacturer-specific powertrain diagnostic trouble code that indicates a problem with the EGR (exhaust gas recirculation) system, specifically the differential pressure feedback sensor (DPFE) circuit. This code is triggered when the PCM (powertrain control module) detects an issue with the upstream hose of the DPFE sensor.

Urgency and Safety

STOP DRIVING IMMEDIATELY. When the P1405 code is triggered, it's critical to stop driving the vehicle and have it towed to a repair shop or dealership. Continuing to drive with an EGR system malfunction can lead to poor engine performance, increased emissions, and potentially severe catalytic converter damage.

Code Specifics

The exact definition of P1405 may vary slightly between vehicle makes and models. However, in most cases it indicates:

• DPFE sensor upstream hose off or plugged
• Exhaust gas recirculation (EGR) valve position sensor malfunction
• EGR valve circuit overheat

Refer to your vehicle's service manual for the specific code definition.

Role of Affected Parts

The EGR system reduces NOx emissions by recirculating a portion of the exhaust gases back into the intake manifold. Key components include:

• EGR Valve: Controls the flow of exhaust gases into the intake manifold. Typically operated by engine vacuum and the PCM.
• DPFE Sensor: Measures pressure differences between the exhaust and intake systems to provide feedback on EGR flow to the PCM. Uses two hoses (upstream and downstream) connected to the exhaust and intake.

Common Causes

Potential causes of a P1405 code include:

1. Damaged, disconnected, or plugged DPFE sensor upstream hose
2. Faulty DPFE sensor
3. Malfunctioning EGR valve
4. Wiring issues in the DPFE sensor circuit
5. Leaks in the EGR system
6. Clogged EGR passages
7. PCM failure (rare)

Diagnosis Steps

1. Scan for other trouble codes. P0401 (insufficient EGR flow) often accompanies P1405.
2. Visually inspect the DPFE sensor upstream hose for damage, kinks, or clogs. Ensure it's securely connected.
3. Perform a smoke test or spray carb cleaner around the EGR system to check for leaks.
4. Test the DPFE sensor operation using a digital multimeter or scan tool.
5. Inspect the EGR valve for proper operation and clogging. Clean if needed.
6. Check wiring and connections in the DPFE circuit for damage or corrosion.
7. If no other issues are found, suspect a faulty PCM.

Repair Solutions

• Replace damaged or plugged DPFE sensor upstream hose
• Clean or replace clogged EGR valve and passages
• Replace faulty DPFE sensor (≈$50 USD / ≈€45 EUR for the part)
• Repair damaged wiring in the DPFE circuit
• As a last resort, replace the PCM if faulty

Prevention and Costs

Regular maintenance, including replacing the EGR valve when needed (every 50,000-80,000 miles or 80,000-130,000 km), can prevent P1405 issues. Repair costs vary:

• DPFE sensor hose: $10-$25 USD / €9-€23 EUR
• EGR valve cleaning: $50-$150 USD / €45-€135 EUR
• EGR valve replacement: $200-$500 USD / €180-€450 EUR
• PCM replacement: $500-$1500 USD / €450-€1350 EUR
• Typical shop labor: $80-$120 USD/hr / €72-€108 EUR/hr

By promptly addressing EGR system issues when the P1405 code appears, you can minimize repair costs and prevent more severe engine damage. Always consult a professional mechanic for an accurate diagnosis and repair.

Frequently Asked Questions about P1405

What does the P1405 code mean?

The P1405 code indicates a problem with the differential pressure feedback (DPFE) sensor circuit, specifically an issue with the upstream hose being disconnected or plugged.

Is it safe to drive with a P1405 code?

No, you should stop driving immediately when the P1405 code appears. Continuing to drive can lead to poor engine performance, increased emissions, and potentially severe catalytic converter damage.

What are the common symptoms of a P1405 code?

Symptoms may include the check engine light illuminating, rough idle, poor acceleration, increased fuel consumption, and a strong smell of fuel.

Where is the DPFE sensor located?

The DPFE sensor is typically located on the driver's side of the engine compartment, about halfway down the bank.

What is the function of the DPFE sensor?

The DPFE sensor measures pressure differences between the exhaust and intake systems to provide feedback on EGR flow to the powertrain control module (PCM).

What are the common causes of a P1405 code?

Common causes include a damaged, disconnected, or plugged DPFE sensor upstream hose, faulty DPFE sensor, malfunctioning EGR valve, wiring issues, leaks in the EGR system, clogged EGR passages, and rarely, a faulty PCM.

How do you diagnose a P1405 code?

Diagnosis steps include scanning for other codes, visually inspecting the DPFE sensor hoses, performing a smoke test for leaks, testing the DPFE sensor operation, inspecting the EGR valve, checking wiring, and suspecting a faulty PCM if no other issues are found.

Can a P1405 code cause other engine problems?

Yes, if left unaddressed, a P1405 code can lead to catalytic converter damage, poor fuel economy, and increased emissions.

What are the common repairs for a P1405 code?

Common repairs include replacing a damaged DPFE sensor hose, cleaning or replacing a clogged EGR valve and passages, replacing a faulty DPFE sensor, repairing damaged wiring, and possibly replacing the PCM.

How much does it typically cost to repair a P1405 code issue?

Repair costs can vary, but expect to pay around $10-$25 for a DPFE sensor hose, $50-$150 for EGR valve cleaning, $200-$500 for EGR valve replacement, $50 for a DPFE sensor, and $500-$1500 for a PCM replacement, plus $80-$120 per hour for labor.

Can a P1405 code clear itself?

While it's possible for the code to clear if the underlying issue is intermittent, it's unlikely and not advisable to wait for this to happen. Always diagnose and repair the problem promptly.

Is the P1405 code specific to certain vehicle makes or models?

The P1405 code is most commonly associated with Ford vehicles but can appear in other makes and models with similar EGR system designs.

What other codes may accompany a P1405?

Related codes that may appear alongside P1405 include P0401 (insufficient EGR flow), P0402 (excessive EGR flow), P0405 (EGR sensor A circuit low), and P0406 (EGR sensor A circuit high).

Can a malfunctioning MAF sensor cause a P1405 code?

While a dirty or faulty mass airflow (MAF) sensor can cause fuel trim issues that may affect EGR operation and trigger oxygen sensor codes, it is not a direct cause of P1405.

How often should the EGR valve be replaced to prevent P1405 issues?

As a preventive measure, the EGR valve should be replaced every 50,000 to 80,000 miles (80,000 to 130,000 km).

Can a vacuum leak cause a P1405 code?

Yes, vacuum leaks in the EGR system can lead to incorrect pressure readings from the DPFE sensor, potentially triggering a P1405 code.

Is it possible to clean the DPFE sensor instead of replacing it?

While cleaning the DPFE sensor may temporarily resolve the issue, it's generally recommended to replace the sensor if it's determined to be faulty.

Can a P1405 code affect vehicle emissions testing?

Yes, a vehicle with an active P1405 code will likely fail an emissions test due to the EGR system malfunction.

How does the EGR system help reduce vehicle emissions?

The EGR system reduces the formation of nitrogen oxides (NOx) by recirculating a portion of the exhaust gases back into the intake manifold, lowering combustion temperatures.

Is it possible for a P1405 code to be triggered by a faulty PCM?

While rare, a faulty PCM can cause a P1405 code to be stored. This should only be suspected after all other potential causes have been investigated and ruled out.