My engine is a four-cylinder. How can it have a bank 2 code?

It cannot, and that is the useful part of the answer. A four-cylinder has one cylinder bank and one exhaust manifold, so there is no second bank for a sensor to sit on. A stored P0547 on that engine almost always means the definition came from a generic code table rather than the manufacturer's, the module is running software for a different engine in the family, or the record was read from another vehicle. Have the code re-read with manufacturer-specific definitions before spending anything.

Why is the quote so much higher than for the bank 1 sensor?

Because you are paying for access, not for the part. The two sensors are frequently the same component at the same price. On a transverse V6 the bank 1 sensor may be reachable from above in twenty minutes while its bank 2 twin sits between the engine and the firewall, behind the intake manifold, in a space you cannot get a hand into. Removing the intake to reach it is several hours of labor plus gaskets. The difference is real, and asking the shop to explain the access path is a fair question that should get a straight answer.

Only one bank has a fault. Why did the whole vehicle lose power?

Because the protections these sensors feed are vehicle-level rather than bank-level. Soot accumulates in a single particulate filter that both banks exhaust into, so the module will not run a regeneration if any of its temperature inputs are untrustworthy — half a picture is not enough to safely command a hot burn. Similarly, a derate is applied to the engine as a whole because there is no way to reduce load on one bank only. One missing input costs you the whole strategy.

Which side of the engine is bank 2?

The side that does not contain cylinder number one. That sounds simple until you try to work out where cylinder one is, which is entirely up to the manufacturer — some number from the front of the engine, some from the accessory drive end, and transverse installations turn the whole thing sideways. Look it up for your specific engine rather than guessing from the code, because a wrong guess here means an expensive part fitted to the wrong side and the original fault still stored.

OBD-II trouble code

P0547: Exhaust Gas Temperature Sensor Circuit Bank 2 Sensor 1

A circuit fault on the exhaust temperature sensor for the second cylinder bank. The first thing worth establishing is whether the engine even has a second bank, and the second is that on most vehicles this is the harder of the two sensors to reach.

Medium severityPowertrainExhaust / AftertreatmentDrivable short-term

Quick facts

System: Powertrain
Category: Exhaust / Aftertreatment
Severity: Medium severity
Drivable: Usually safe to drive short-term
Repair cost range: $160 – $1,200
DIY difficulty: Advanced DIY

What does P0547 mean?

Bank 2 is not a component. It is a naming convention, and it only exists on engines whose cylinders are split into two separate groups with two separate exhaust paths — V6, V8, V10 and flat or boxer layouts. An inline four or inline six has one bank, one manifold and no bank 2 at all. That fact is the first thing to settle when this code appears, because a genuine P0547 on an inline engine is not a sensor problem: it points at a module carrying software for the wrong engine variant, a scan tool matching a generic code table rather than the manufacturer's, or a history record read out of a different vehicle. Confirming the engine layout costs nothing and prevents an expensive search for hardware that was never fitted.

Assuming the engine does have two banks, bank 2 is the side that does not contain cylinder number one, and sensor 1 is the first temperature sensor in that side's exhaust flow — before the turbine on a turbocharged application, before the first catalyst on a naturally aspirated one. The measurement principle is the same as on bank 1: reference voltage out, signal voltage back, resistance converted to degrees. P0547 means that circuit is not behaving electrically the way the module requires. On many applications this is the general circuit code, set for a fault the module cannot resolve into a specific low or high condition, or for a signal that is unstable rather than pinned.

Where bank 2 genuinely differs is in what it costs to work on and what a bank-2-only fault implies. On transverse V6 engines — the layout in a large share of front-wheel-drive crossovers and minivans — bank 2 is conventionally the rear bank, tucked against the firewall behind the intake manifold. The sensor is the same part number as its bank 1 counterpart and costs the same money, but reaching it can mean removing the intake, lifting the engine on its mounts, or working from underneath with almost no visibility. A quote that is two or three times the bank 1 figure for the identical component is not padding.

The second real difference is diagnostic direction. On a twin-turbo V engine each bank has its own turbocharger with its own temperature sensor guarding it. A fault confined to bank 2 therefore points at one turbo's plumbing, one bank's harness branch and one connector — not at the shared aftertreatment further downstream, which both banks feed into. If the complaint were coming from the filter or catalyst, both banks would generally be implicated. A single-bank code narrows the search to everything upstream of where the two exhaust paths merge, which is a genuinely useful boundary.

Common causes

Failed exhaust gas temperature sensor on the bank 2 side with an unstable or out-of-range element
Harness damage on the bank 2 branch, which on transverse engines has to cross the engine bay and is longer than its bank 1 counterpart
Connector corrosion or a partially seated plug on the less accessible side, where it is rarely inspected
Heat damage to the lead where it passes the second turbocharger or the rear exhaust manifold
Chafing where the bank 2 harness branch passes over or behind the engine and moves with engine rock
Damage from a previous rear-bank spark plug, manifold or intake removal that disturbed the harness routing
Software or calibration mismatch on an engine that has no bank 2, which sets the code without any hardware fault
Module or reference supply fault, which should only be suspected once both the sensor and its wiring are proven

Symptoms

Check engine light with the engine otherwise running normally
Bank 2 exhaust temperature in live data reading implausibly, or dropping out and returning while bank 1 stays steady
Regeneration not running on a diesel application, even though only one bank is unmonitored
Reduced power or a protective derate on applications that treat any unverified exhaust temperature as a reason to limit fuel
Soot load rising with no successful regeneration recorded
Boost imbalance complaints on twin-turbo applications where the module backs off one side
Fault appearing shortly after work that required removing the intake manifold or reaching the rear bank
Increased fuel consumption as the module runs a conservative strategy without a full set of temperature inputs

Diagnostic steps

1.Confirm the engine physically has two banks before anything else. Count the exhaust manifolds. On an inline engine there is one, there is no bank 2, and a stored P0547 is a calibration or lookup problem rather than a wiring problem — chasing hardware at that point wastes hours.
2.Identify which side is bank 2 using the manufacturer's cylinder numbering rather than assuming. Bank 2 is the side without cylinder one, and which physical side that is varies between makes and even between engine families from the same make. Getting this backwards means replacing a perfectly good sensor on the accessible side.
3.Compare bank 1 and bank 2 exhaust temperatures side by side in live data after a cold soak. With the engine cold both should sit close to ambient and close to each other; a divergence of hundreds of degrees between two sensors seeing the same still air is a circuit fault you can identify without a specification sheet.
4.Follow the bank 2 harness branch across its whole length. On transverse engines this branch has to travel around or over the engine to reach the main harness, so it is longer, passes more heat sources and moves with engine rock. Pay particular attention to any point where it is clamped, because that is where a flexing conductor breaks.
5.Wiggle-test the connector and the branch with live data displayed and the engine idling. An unstable circuit that responds to being disturbed is a connection problem, and finding it this way is far quicker than measuring a circuit that happens to be intact at the moment you test it.
6.Plan access before quoting or committing. On a rear-bank sensor, establish whether the intake has to come off or the engine has to be rolled forward, because that decision is the entire difference between a one-hour job and most of a day on an otherwise identical part.

Repair cost

$160 – $1,200

The part is ordinary — usually $45 to $250, the same as the bank 1 sensor — and everything above that is access. A bank 2 sensor that can be reached from underneath on a longitudinal engine is a $200 to $450 job. A rear-bank sensor on a transverse V6 that requires intake removal or lifting the engine can reach $700 to $1,200, and that figure is honest rather than inflated. Wiring repair on the bank 2 branch runs higher than the bank 1 equivalent for the same reason: the branch is longer and half of it is not visible. If the threads seize and the sensor snaps, add $150 to $400 for extraction on top.

Estimate your repair

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Open the Repair Cost Estimator with exhaust gas temperature (egt) sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.

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DIY vs shop

This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.