P1600

ECM BATT Malfunction

Car Fault Codes Toyota Engine computer & electrical

Can you still drive? Yes, normally

Who can fix it? Needs a workshop

Typical repair time 15 minutes – 4 hours

Typical cost SAR 50 to 5,000

What it means

This is a Toyota-specific code; other makes may use the number differently. The engine computer receives a constant battery feed (BATT) to keep its memory and learned values while the car is off, and it detected that this feed was lost. The code may appear once after the battery is disconnected or replaced, but if it keeps returning there is a fuse or wiring problem.

Models covered: Toyota models of the 1990s to mid-2000s.

Symptoms4

Check engine light on.
Unstable or high idle after each start because learned values are lost.
Emissions readiness monitors do not complete.
There may be no other symptoms.

Possible causes5

Battery recently disconnected or replaced.
Blown fuse feeding the computer memory.
Loose or corroded battery terminals.
Open or corroded constant-feed wire or computer connector.
Internal engine computer fault.

How to diagnose5

Ask whether the battery was disconnected recently; if so, clear the code and see if it returns.
Check that the battery terminals are clean and tight.
Check the fuse feeding the computer using the fuse chart in the owner's manual.
Measure battery voltage at the constant-feed terminal of the computer connector with the ignition off.
If the feed is good and the code returns, have the computer checked by a specialist.

How to fix5

Clear the code after a battery disconnect and leave it if it does not return.
Clean and tighten the battery terminals.
Replace a blown fuse after finding why it blew.
Repair the feed wire or connector.
Replace and program the engine computer only if an internal fault is proven, then clear codes and confirm they stay away.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

Clearing the code, cleaning terminals or replacing a fuse usually does it at low cost; the top of the range is a computer replacement with programming, which is rare.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

P1600 appeared after a battery change. Is that normal?

On many older Toyotas the code can be logged after the feed is interrupted. Clear it and watch the car; if it does not return, there is no problem.

Why is the idle unstable with this code?

The computer loses its learned idle and fuel values every time the feed drops, so it starts relearning after each start.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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