ECM BATT Malfunction
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.
Related lights
Dashboard lights that may come on with this code.
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
In Saudi riyals; the highlighted part is the expected range for this fault.
In the Saudi market: SAR 50–5,000 (≈ USD 13–1,330)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
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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