AutoCodes – Mercury – P1605 Mercury

P1605 Mercury Code - PCM Keep Alive Memory Test Error Conditions

Quick Answer

With the Key On Engine Off (KOEO) the Diagnostic Trouble Code (DTC) P1605 indicates Powertrain Control Module (PCM) has experienced power interrupt in the keep-alive power circuit. Common causes include Low battery charge, Faulty Powertrain Control Module (PCM), Powertrain Control Module harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1605 Mercury indicates PCM Keep Alive Memory Test Error Conditions.
Common causes: Common causes include Low battery charge, Faulty Powertrain Control Module (PCM), Powertrain Control Module harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,514

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Sep 30, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
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Code P1605 Mercury Description

OBDII Code P1605 Mercury - PCM Keep Alive Memory Test Error Conditions - AutoCodes.com — P1605 Mercury Code - PCM Keep Alive Memory Test Error Conditions

What does this mean?

What are the Possible Causes of the DTC P1605 Mercury?

Low battery charge
Faulty Powertrain Control Module (PCM)
Powertrain Control Module harness is open or shorted
Powertrain Control Module circuit poor electrical connection

How to Fix the DTC P1605 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1605 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1605 Mercury Code

1. What does the OBDII code P1605 mean for a Mercury vehicle?

P1605 indicates a "PCM Keep Alive Memory Test Error," meaning the Powertrain Control Module (PCM) has detected an issue with retaining memory when the vehicle is off.

2. What are the common symptoms of code P1605 in a Mercury?

Symptoms can include a check engine light, poor engine performance, difficulty starting, or loss of previously stored adaptive data like fuel trims.

3. What causes the P1605 code to be triggered?

Common causes include a weak or disconnected battery, faulty PCM, damaged wiring, or issues with the keep-alive memory (KAM) circuit.

4. Can a low battery cause the P1605 code on a Mercury?

Yes, a low or failing battery can cause the PCM to lose its memory, triggering the P1605 code.

5. How do I fix the P1605 code on my Mercury?

Start by checking the battery and charging system. Repair or replace any damaged wiring or connections. If the issue persists, the PCM may need reprogramming or replacement.

6. Can I drive my Mercury with the P1605 code?

While the vehicle may still be drivable, you could experience performance issues, and prolonged driving with this code may lead to further complications.

7. How do I reset the PCM Keep Alive Memory on a Mercury?

Disconnect the negative battery terminal for about 15 minutes, then reconnect it. This will clear stored data, but it won't address the underlying issue causing the P1605 code.

8. Does the P1605 code always mean the PCM is faulty?

No, a faulty PCM is just one possible cause. Always check the battery, wiring, and connections before replacing the PCM.

9. How much does it cost to repair a P1605 code on a Mercury?

Costs vary depending on the cause, but battery replacement typically costs $100-$200, while PCM replacement and programming can range from $500-$1,500.

10. Can an aftermarket battery trigger the P1605 code?

Yes, if the battery's voltage is inconsistent or if installation caused poor connections, it can lead to memory retention issues and trigger the code.