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2007 Toyota Corolla P0607 Code: Causes, Symptoms & PCM Failure Diagnosis

Model: 2007 Corolla Fault Code: P0607 Posted: 2009-11-12 19:50

Hello everyone, I'm new here and recently came across this forum through a friend. I currently own a 2007 Toyota Corolla that's been throwing several random OBD-II diagnostic codes: P0121, P0122, P0400, P0607, and P0606. These codes appear at different times and have no connection to driving conditions. The most puzzling part is that when I disconnect the battery or unplug the Powertrain Control Module (PCM), the codes disappear and the Check Engine Light does not come back on. This issue started after I refilled my gas tank, which was only slightly below half full. I'm wondering what could be causing this behavior. Given that the codes persist even after power cycling, and especially with P0607 and P0606 appearing repeatedly, I suspect a potential PCM failure — as these codes often indicate module-level issues. I'd appreciate any insights into possible root causes, diagnostic steps, or whether there might be another underlying issue related to fuel levels or sensor performance.

Related fault codes

P0607

Comments (5)

Anonymous 2009-11-12 21:21

First, I strongly recommend avoiding clearing codes by disconnecting the battery or unplugging the PCM. Doing so can mask real issues and lead to misdiagnosis. When the Check Engine Light returns, perform a full scan to identify which code is active. Since P0607 and P0606 are both related to PCM functionality, these should be your top priority for diagnosis. It's normal that the light doesn't come back on after disconnecting the PCM — this happens because OBD-II systems store diagnostic trouble codes (DTCs) in non-volatile memory, so they don’t reset automatically when power is removed.

Anonymous 2009-11-13 06:08

I've experienced similar no-start issues where there's no injector pulse, no fuel pump activation, and no coil signal. When the vehicle fails to start, my scan tool also cannot connect to the system. However, after unplugging the PCM for a short period and reconnecting it, the car starts normally and runs for about 5–10 minutes before the Check Engine Light illuminates and then shuts down abruptly. This behavior strongly suggests a malfunctioning PCM or communication failure between modules.

Anonymous 2009-11-13 06:22

That sounds very much like a failing Powertrain Control Module (PCM). I'd suspect that when the vehicle fails to start, the Check Engine Light does not illuminate at all — if it does, it may indicate intermittent signal issues rather than complete failure.

Anonymous 2009-11-13 21:17

The vehicle does show a Check Engine Light during no-start events, but it won’t start. Additionally, scan tools fail to initialize when the car is in this state. I’ve heard that replacing the PCM requires reprogramming with the correct VIN — is there an affordable tool available for this process? I don't currently own one.

Anonymous 2009-11-13 22:34

There is generally no affordable tool capable of performing a full VIN transfer or PCM reprogramming. Such functions are typically only supported by high-end professional-grade scan tools, often found in dealerships or advanced repair shops. Before considering a PCM replacement, it's important to verify whether the issue falls under Toyota’s emissions warranty and ensure that all wiring and circuit connections to the module are intact — a qualified diagnostic technician should perform these checks before condemning the PCM.