No.1 secondary injector circuit malfunction
The No.1 secondary injector circuit did not respond as commanded (open or short). Standard Honda meaning.
- Manufacturer
- Honda
- Platform
- PGM-FI (Keihin, Renesas M32R)
- Models
- CBR600RR
- Years
- 2003-2022
- Subsystem
- No.1 secondary injector circuit
- FI-light blink
- 1 long, 6 short
- Hex
- 0x1601
Strongly inferred. Strongly inferred: the standard Honda meaning is well established, but exactly how this ECU handles it internally is inferred rather than fully confirmed.
What it means
The CBR600RR uses extra (secondary) injectors that come in at higher load. This is the same injector-circuit check as the primaries, applied to the No.1 secondary injector.
Conditions
Detection conditions
- The ECU drives the No.1 secondary injector and checks the circuit responds.
Sets the fault when
- The circuit stays open or shorted long enough to count.
Clears the fault when
- Fix the underlying problem, then clear the stored codes with a diagnostic tool or the manufacturer’s reset procedure. If the fault is still present, the code returns the next time the ECU detects it.
Parts involved
- No.1 secondary fuel injector and its wiring
Symptoms & likely causes
Possible symptoms
- FI (check-engine) light on
- Reduced high-load fuelling or a top-end misfire on that cylinder
Likely causes
- Open or shorted secondary injector
- Wiring or connector fault
Diagnostic guidance
Secondary injectors mainly matter under load, so symptoms may only show at higher rpm.
How the ECU decides
A simplified view of the logic behind this code: a short C snippet with a plain-English summary. It shows the real decision the ECU makes without the low-level detail.
For an output like an injector, coil, or sensor heater, the ECU switches the circuit on and checks that it actually responded. If the circuit is open or shorted for long enough, it sets the code and stops driving that output.
// Command the output on, then confirm the circuit responded.
turn_on(output);
if (circuit_response(output) == BAD) { // open or short
bad_count++;
if (bad_count >= limit)
set_fault();
}
When the ECU confirms a fault, it saves the code and turns on the FI (check-engine) light. For a serious fault it also runs the engine on safe default values (limp-home) so you can still ride, with the light on.
// Once a fault is confirmed, remember it and warn the rider.
if (fault_confirmed) {
store_code(code); // kept until the codes are cleared
fi_light = ON;
if (fault_is_serious)
limp_home = ON; // safe defaults so you can ride home
}
Related codes
Questions about code 16-01
- What does Honda code 16-01 mean?
- The No.1 secondary injector circuit did not respond as commanded (open or short). Standard Honda meaning.
- Which motorcycles does code 16-01 apply to?
- It is documented here for the Honda CBR600RR (2003-2022). Other Honda models may use the same display code with a different meaning, so confirm against your model.
- Can I still ride with code 16-01?
- It depends on the fault. Code 16-01 relates to the No.1 secondary injector circuit. If the bike runs poorly or a safety-related system is affected, avoid riding until it is checked. The FI light stays on until the fault is fixed and the codes are cleared.
- What should I check first for code 16-01?
- Secondary injectors mainly matter under load, so symptoms may only show at higher rpm.
Sources
Every technical claim on this page traces to the research below. Source labels are sanitized; no local research paths are exposed.
- firmware
2005-2006 Honda CBR600RR ECU firmware
Factory PGM-FI firmware for the 2005-2006 CBR600RR. Primary source of truth.
- analysis
Firmware fault-code table extraction
Reads the list of codes the ECU can store directly out of each firmware.
- reference
HondaECU project (open-source Honda ECU tool)
Community reference mapping Honda PGM-FI codes to their meanings.
- analysis
CBR600RR ECU reverse-engineering analysis
Independent analysis of how the ECU detects, stores, and reports faults.