OBD-II Code
P1604
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$25–$980
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P1604 on Toyota is Startability Malfunction, which the ECM sets when extended cranking, multiple crank attempts, or rough running during the first 5 to 20 seconds after start exceeds calibrated thresholds; it's a symptom-class code rather than a specific-component code.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP1604 on Toyota is Startability Malfunction, which the ECM sets when extended cranking, multiple crank attempts, or rough running during the first 5…
P1604 on Toyota is Startability Malfunction, which the ECM sets when extended cranking, multiple crank attempts, or rough running during the first 5 to 20 seconds after start exceeds calibrated thresholds; it's a symptom-class code rather than a specific-component code. The ECM is essentially saying the engine is hard to start or runs poorly on cold start, and the actual root cause sits in fuel pressure, ignition energy, compression, sensor drift, or cold-start enrichment logic.
Cheapest ladder
- scan for any concurrent codes first (P0171/P0174 lean, P0300-P030X misfire, P0420 cat efficiency) because P1604 frequently sets alongside the real fault.
- Verify fuel pressure on key-on, engine-off (most port-injected Toyotas spec 38 to 44 psi for at least 5 minutes), inspect for fuel injector seepage by cycling key-on three times then watching pressure decay, and pull the spark plugs to check condition (look for fuel-fouled plugs indicating a leaking injector, or oil fouling indicating valve guide wear).
- The expensive misdiagnosis is replacing the cam timing components or pulling the engine on suspected compression loss when the actual fault is a single leaking fuel injector that bleeds rail pressure overnight.
Vehicle-specific patternsToyota 2GR-FE 3.5L V6 (Camry, Avalon, Sienna, Highlander 2007-2014) sees P1604 commonly from leaking fuel injectors that drain rail pressure between…
Toyota 2GR-FE 3.5L V6 (Camry, Avalon, Sienna, Highlander 2007-2014) sees P1604 commonly from leaking fuel injectors that drain rail pressure between starts. Toyota 2AZ-FE 2.4L (Camry, RAV4 2002-2009) sets P1604 from a combination of carbon-fouled injectors and the engine's known oil-consumption-driven plug fouling. Toyota 1NZ-FE 1.5L (Prius NHW11/20, Echo, Yaris 2000-2012) sets P1604 most often from a drifting ECT sensor giving the ECM bad cold-start enrichment data. Toyota 2JZ-GE and 1JZ-GTE (Supra, GS300, IS300 1993-2005) sees P1604 from aging fuel pressure regulator diaphragms leaking fuel into the intake vacuum.
Estimated repair$25 to $980.
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