P0545: Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 1

The exhaust gas temperature sensor is a thermistor in a voltage divider with the module's pull-up resistor; the first one (sensor 1) sits before the turbocharger, the oxidation catalyst or after it depending on the maker. Diesels use it for particulate filter regeneration and component protection; CARB names it explicitly as a monitored input. P0545 means the signal is below range: GM L5P below 142 Ω in 10 of 20 samples, GM LML below 0.65 V, Ford 6.7 L below 0.10 V for about 2 s, Saab 9-5 2.0 TiD below 0.1 V for 1 s. Usually a signal shorted to ground. GM USA uses two trips, GM Europe in the Saab one. The module uses a substitute value and blocks filter regeneration.

Medium severity. Can I keep driving?If the light is on steadily, take a highway drive or go to a repair shop soon. If the car is in limp mode or the light is flashing, do not push the engine.

Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.

Symptoms

Check engine light on
Particulate filter regeneration missing, filter warning
Possible power reduction

Most likely causes

Signal line shorted to ground (chafed on the exhaust or bracket)
Sensor shorted internally
Connector damp or corroded
Engine module

What to check, in order

Start with the simplest. You can tick off each step.

Read the soot load and differential pressure with a scanner
With the connector unplugged, check whether the signal wire is making contact with ground.
Check the differential pressure sensor's hoses
Check the temperatures before and after the filter
Fix any fuel injection or EGR codes before regenerating
Perform a regeneration while driving or at a repair shop when the diagnosis allows it

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P0545 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
5: Speed and idle
45: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0545?

If the light is on steadily, take a highway drive or go to a repair shop soon. If the car is in limp mode or the light is flashing, do not push the engine.

What causes code P0545?

The most common causes are: signal line shorted to ground (chafed on the exhaust or bracket); sensor shorted internally; connector damp or corroded.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.