B1947 Code: Meaning, Symptoms, Causes & Fix

Overview

Code B1947 indicates a fault in Climate Control A/C Post Evaporator Sensor Circuit Short To Ground, typically within emissions and air-fuel control.

Symptoms

failed emissions test readiness
rough idle under load
check engine light

Common causes

Open circuit in wiring affecting climate control a/c post evaporator sensor circuit short to ground
Disconnected or loose connector
Connector pin damage/corrosion or harness stress near related components

How to diagnose B1947

Confirm B1947 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to climate control a/c post evaporator sensor circuit short to ground for obvious defects.
Use a continuity test from module pin to component to identify opens/high resistance.
Check for related DTCs to identify the root-cause chain before replacing parts.
After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code B1947

Moderate: This code is moderate severity: the vehicle may still operate, but fault progression can increase repair cost over time.

Can you drive with B1947?

Most vehicles can be driven short-term with B1947, but postpone heavy load/highway driving until repaired.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (open) in the climate control a/c post evaporator sensor circuit short to ground circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify B1947 remains cleared under the conditions that originally set the code.

Fix options

Clear corrosion and protect terminals.
Repair open circuit and secure connector lock.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$180-$900

Common mistakes when diagnosing B1947

Replacing parts without verifying voltage, ground, and signal integrity first.
Ignoring related stored/pending codes that indicate upstream faults.
Skipping post-repair verification drive cycle and readiness checks.

B1947 in common vehicles

B1947 appears across makes such as Mazda, Subaru, Lexus, Jeep. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes B1947?

B1947 is commonly set by open faults affecting climate control a/c post evaporator sensor circuit short to ground.

How much does it cost to fix B1947?

For B1947, repair costs are typically $180-$900 depending on exact root cause, labor rates, and part quality.

Can I clear B1947 without repair?

You can clear B1947 temporarily, but the code usually returns until the underlying fault is corrected.