C1A16: Radar sensor blocked or obstructed (Nissan)
Nissan front radar blocked / radar stain
Severity: Inspect soon
Owners report forward emergency braking and intelligent cruise switching off, and in some cases unexpected braking, so the driver-assist safety systems cannot be relied on.
C1A16 in short
On Nissan vehicles, C1A16 means the front radar behind the grille is blocked or stained, so forward emergency braking and intelligent cruise switch off. Owners report dealers cleaning, realigning, reprogramming or replacing the radar. Drive without relying on the driver-assist systems and have it checked.
Nissan owners on Rogue, Altima and Sentra quote dealers giving C1A16 as a blocked or obstructed radar sensor, "radar stain" or "radar blocked". Warning lights for emergency braking and cruise come on.
Some complaints add that the dealer reprogrammed the radar, aligned it or replaced the unit, and a few owners say the fault came back. A Rogue Sport owner says the dealer noted to keep the grille sensor clean of debris.
Because the radar also drives forward emergency braking, owners describe unexpected braking or loss of the assist. Other makes may use C1A16 differently; we have not verified them.
Pick your make
C1A16 is a manufacturer-specific code: its meaning depends on who built the car.
Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.
Most likely causes
Cause 1: Radar sensor blocked, dirty or out of alignment
Supported by vehicle data- Why it ranks here
- Dealer readouts in three Nissan complaints describe a blocked or stained radar and an alignment or reprogram.
- What would change this
- Rises if the fault clears when the grille area is cleaned or the radar is realigned. Falls if it returns with a clean sensor.
Cause 2: Radar unit fault
Supported by vehicle data- Why it ranks here
- One Altima dealer quoted a replacement radar after reprogramming failed.
- What would change this
- Rises if realignment and reprogramming do not help. Falls if cleaning or alignment fixes it.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Have the radar area behind the grille checked for dirt, damage or misalignment and its codes read.
Warning:Emergency braking is a safety system. Have a dealer or shop check and align the radar.
IfThe sensor area is dirty or blocked
It meansRadar blocked.
IfIt is clean and the fault returns after alignment or reprogramming
It meansThe unit may need replacing.
Symptoms
- Emergency braking or intelligent cruise warning light on
- Radar blocked message in the display
- Unexpected braking with nothing ahead Gets more serious: stop and have it checked.
How to fix
This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.
On your vehicle
NissanYour car
2018 · Altima
Supported by vehicle dataAn owner reports a dealer finding C1A16 radar stain and C1B55-97 radar blockage, reprogramming the radar and then quoting a replacement.
2017 · Rogue
Supported by vehicle dataAn owner reports the dealer saying C1A16-97 relates to a blocked or obstructed radar sensor, stored as a past code.
Related codes
No curated relationships for C1A16 yet.
C1A16 questions
Can I clean the radar myself?
A dealer in one complaint told the owner to keep the grille sensor clean of debris, but this is a safety system, so have a shop check or align it if the fault returns.
Sources and review
- NHTSA complaint ODI 11057739: 2017 Nissan Rogue warning message
- NHTSA complaint ODI 11278863: 2018 Nissan Altima driver assist
- NHTSA complaint ODI 11407961: 2019 Nissan Sentra emergency braking lights
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error