What Does P0437 Mean?
The catalyst temperature sensor on bank 2, sensor 1 (pre-catalyst or at-catalyst position) is reading below the minimum expected voltage. This indicates a potential short to ground in the circuit, a failed sensor, or a wiring problem pulling the signal low. The PCM cannot accurately monitor catalyst temperature and the MIL will be set.
Common Causes
35%
Failed catalyst temperature sensor shorted internally to ground
30%
Signal wire shorted to ground due to heat-damaged insulation
20%
Corroded connector allowing signal to bleed to ground
10%
Water intrusion in the connector or wiring splice
5%
PCM sensor input circuit pulled low internally
Diagnostic Steps
1
Check the sensor signal voltage at the PCM connector with KOEO — if the voltage is below 0.2V, confirm the low circuit condition. Typical idle reading should be 0.5–4.5V depending on temperature.
2
Disconnect the sensor and check if the signal voltage at the harness connector rises to near 5V reference — if it does, the sensor is shorted internally and needs replacement.
3
If the voltage remains low with the sensor disconnected, check the signal wire for continuity to ground — a short to ground in the harness will keep the voltage low regardless of sensor condition.
4
Inspect the wiring harness routing near the exhaust manifold and catalytic converter for melted insulation or bare wire touching the chassis/exhaust.
5
Check for water intrusion in the connector — separate the connector halves and look for green corrosion or moisture on the terminals.
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
The catalyst temperature sensor on bank 2, sensor 1 (pre-catalyst or at-catalyst position) is reading below the minimum expected voltage. This indicates a potential short to ground in the circuit, a failed sensor, or a wiring problem pulling the signal low. The PCM cannot accurately monitor catalyst...
The most common cause of P0437 (Catalyst Temperature Sensor Circuit Low (Bank 2, Sensor 1)) is: Failed catalyst temperature sensor shorted internally to ground
Typical repair costs for P0437 range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. Catalyst temperature monitoring is non-functional, meaning an overheating condition would not be detected. If you smell strong sulfur or notice unusual heat from the floorboard, stop and inspect immediately.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0437 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Exhaust / Catalytic Converter
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
