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P0605 Code Reappears After New ECM Installation - 2004 Nissan Sentra 1.8L

Model: Nissan Sentra Fault Code: P0605 Posted: 2014-07-17 22:57

I'm experiencing a persistent P0605 code on my 2004 Nissan Sentra 1.8L, and despite replacing the ECM, the issue continues. The check engine light activates, and the vehicle enters safe mode—disabling throttle operation—even though it idles fine initially. This model uses an electric throttle system (fly-by-wire), so when the P0605 code is detected, the ECM shuts down throttle control to prevent unsafe driving conditions. After turning off the car for about an hour, it will start and run normally for 3–5 miles before the same error reappears and throttle shutdown occurs again. According to the factory service manual, P0605 (Internal Control Module Read-Only Memory Error) is caused by only three potential issues: 1. A faulty ECM 2. Shorted or open power supply 3. Shorted or open ground I replaced both the original and a new OEM Nissan ECM with proper programming from the dealer. However, after driving approximately 7 miles post-installation, the same P0605 code reappeared. The dealer has thoroughly tested all power supplies, voltage levels, and grounding connections—confirming they are within specifications. They have also contacted the ECM manufacturer for further support but remain unable to resolve the issue. I'm now wondering if there could be a deeper hardware or sensor-related cause beyond just the ECM itself. Any insights from others who've faced this on a 2004 Sentra or similar models? Additional details: - Vehicle: 2004 Nissan Sentra 1.8L, manual transmission, factory stock setup (no aftermarket electrical modifications) - Both ECUs were OEM-certified and programmed correctly - No other diagnostic errors are present during scanning

Related fault codes
P0605
Comments (6)
Anonymous 2014-07-18 11:24

Vehicle is stock with no added electronics. Has anyone encountered this issue with an OEM versus remanufactured ECM? Any specific differences in behavior between the two?

Anonymous 2014-07-18 11:37

The vehicle is completely stock—no modifications, manual transmission, and cruise control is standard. The first ECM was original factory; the second is a new OEM Nissan unit.

Anonymous 2016-01-03 07:47

I now have the same issue on my 2004 Nissan Murano (3.5L V6, automatic). All power and ground connections were tested multiple times, and after replacing with a genuine dealer-grade ECM—no aftermarket or reman unit—the P0605 code reappears shortly after. Full system scan shows no other faults. I own a repair shop and have fixed many similar cases, but this one remains unresolved. Did you ever get to the root cause? I see you're experiencing something very similar.

Anonymous 2016-01-03 07:49

My Murano is a 2004 model with a 3.5L V6, automatic transmission, and no aftermarket wiring or electronic additions—only factory-installed components.

Anonymous 2016-01-03 11:12

The issue was finally resolved: the original ECM, though new, was diagnosed as defective. The dealer technician advised replacing both the brake switch (part #25300-4M400, $42.77) and cruise control switch (part #25320-4M400, $46.60). After these replacements and a new OEM ECM installation—covered under warranty—the vehicle has run flawlessly since. This suggests that faulty switches may interfere with ECM communication or memory initialization. Wishing you the best of luck!

Anonymous 2016-01-11 15:50

Have you tried performing a throttle relearn procedure? On several Nissan models, after disconnecting the battery or cleaning the throttle body, a relearn process is required to restore proper throttle calibration. Some vehicles require a specialized snap-on scan tool or dealer-level access to complete this step—this might be necessary in cases where ECM communication is unstable.