Which motorcycles does code 38-01 apply to?

It is documented here for the Honda CBR600RR (2007-2022). Other Honda models may use the same display code with a different meaning, so confirm against your model.

Can I still ride with code 38-01?

It depends on the fault. Code 38-01 relates to the A/F (air-fuel ratio) sensor heater. 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.

38-01 Strongly inferred

A/F sensor heater malfunction

The air-fuel sensor’s heater circuit had a fault. Present on the 2007-2012 and 2013-2022 CBR600RR only. Standard Honda meaning.

Manufacturer: Honda
Platform: PGM-FI (Keihin, Renesas M32R)
Models: CBR600RR
Years: 2007-2022
Subsystem: A/F (air-fuel ratio) sensor heater
FI-light blink: 3 long, 8 short
Hex: 0x3801

Saw 38-01 as 3 long, 8 short on the FI light? Decode a blink pattern →

All major 38 codes How blink codes work

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

Later CBR600RRs use a wideband air-fuel sensor in place of the earlier oxygen sensor. Like the oxygen sensor, it has a heater the ECU drives and monitors. This code sets when that heater circuit is open or shorted. It is not present on the 2003-2006 bikes.

Conditions

Detection conditions

The ECU drives the air-fuel-sensor heater and checks the circuit responds.

Sets the fault when

The heater 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

Air-fuel (wideband) sensor heater element and its wiring

Symptoms & likely causes

Possible symptoms

FI (check-engine) light on
Air-fuel sensor slow to warm up, so closed-loop starts late

Likely causes

Open or shorted heater element
Heater wiring or connector fault

Diagnostic guidance

Applies to 2007-onward air-fuel-sensor bikes. Diagnose as a heater-circuit open or short.

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.

C How an injector / coil / heater circuit sets a code

1// Command the output on, then confirm the circuit responded.
2turn_on(output);
3if (circuit_response(output) == BAD) {   // open or short
4    bad_count++;
5    if (bad_count >= limit)
6        set_fault();
7}

Reverse-engineered interpretation · CBR600RR ECU reverse-engineering analysis

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.

C How a confirmed fault is stored

1// Once a fault is confirmed, remember it and warn the rider.
2if (fault_confirmed) {
3    store_code(code);      // kept until the codes are cleared
4    fi_light = ON;
5    if (fault_is_serious)
6        limp_home = ON;    // safe defaults so you can ride home
7}

Reverse-engineered interpretation · CBR600RR ECU reverse-engineering analysis

Related codes

Questions about code 38-01

What does Honda code 38-01 mean?: The air-fuel sensor’s heater circuit had a fault. Present on the 2007-2012 and 2013-2022 CBR600RR only. Standard Honda meaning.
Which motorcycles does code 38-01 apply to?: It is documented here for the Honda CBR600RR (2007-2022). Other Honda models may use the same display code with a different meaning, so confirm against your model.
Can I still ride with code 38-01?: It depends on the fault. Code 38-01 relates to the A/F (air-fuel ratio) sensor heater. 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 38-01?: Applies to 2007-onward air-fuel-sensor bikes. Diagnose as a heater-circuit open or short.

Sources

Every technical claim on this page traces to the research below. Source labels are sanitized; no local research paths are exposed.

firmware

2007-2012 Honda CBR600RR ECU firmware

Factory PGM-FI firmware for the 2007-2012 CBR600RR.
firmware

2013-2022 Honda CBR600RR ECU firmware

Factory PGM-FI firmware for the 2013-2022 CBR600RR.
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

Cross-generation Honda DTC comparison (2003-2022)

Which codes appear in each CBR600RR ECU firmware generation.

Content version 1.0.0 · last reviewed 2026-07-14

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