What Does P042D Mean?
The catalyst temperature sensor circuit for bank 1 sensor 2 (post-catalytic converter) is reading higher than the expected voltage range. This typically points to an open circuit, high resistance in the wiring, or an internally failed sensor reading artificially high. The MIL will be on but the driver is unlikely to notice performance issues.
Common Causes
35%
Failed catalyst temperature sensor (open circuit internally)
30%
Open or high-resistance wiring in the sensor signal circuit
20%
Corroded or disconnected sensor connector
10%
Short to voltage in the sensor signal wire
5%
PCM/ECM internal fault on sensor input
Diagnostic Steps
1
Backprobe the catalyst temperature sensor signal wire at the connector — a reading near 5V or reference voltage with the engine at operating temperature confirms an open or high circuit condition.
2
Disconnect the sensor and measure resistance across its terminals. An open-loop reading (OL/infinite) confirms a failed sensor element.
3
With the sensor disconnected, jumper the signal wire to the ground wire at the harness side — if the scan tool reading drops to minimum, the wiring back to the PCM is intact.
4
Inspect the connector for spread terminals, corrosion, or water intrusion that could cause intermittent high resistance connections.
5
Check the sensor ground circuit for continuity back to the PCM ground pin — resistance should be less than 1 ohm.
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
The catalyst temperature sensor circuit for bank 1 sensor 2 (post-catalytic converter) is reading higher than the expected voltage range. This typically points to an open circuit, high resistance in the wiring, or an internally failed sensor reading artificially high. The MIL will be on but the driv...
The most common cause of P042D (Catalyst Temperature Sensor Circuit High (Bank 1 Sensor 2)) is: Failed catalyst temperature sensor (open circuit internally)
Typical repair costs for P042D range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving. The catalytic converter monitoring system is degraded, but vehicle performance and safety are not directly affected. Address before emissions inspection.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P042D to identify the root cause.
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Quick Info
Category
Powertrain
System
Exhaust / Catalytic Converter
Difficulty
Type
Generic (SAE)
Recommended Tools
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