Does it matter whether the 'A' code is stored too?

It is the most useful single fact on the scan report. On most vehicles 'A' and 'B' are two independent tracks reading the same pedal arm or the same throttle shaft, duplicated so the module can catch one of them lying. If only 'B' failed the full-travel check, the assembly clearly did reach its stop — the partner track measuring the same movement said so — which rules out obstructions and travel problems and points at that one track or its wiring. If both failed together, a shared cause is far more likely than two independent sensors failing identically at the same moment.

Why does the car drive normally until I ask for full power?

Because the fault is confined to the top of the range, and the top of the range is only checked when something actually goes there. Idle, town driving and light throttle never approach the maximum stop, so everything you do most of the time behaves exactly as it always has. The code typically appears during a hard merge or an overtake, which is not when the fault started — it is simply the first time the module looked at that end of the travel and disagreed with what it found.

Can I replace just the 'B' sensor?

On most vehicles, no, and it is worth knowing before you shop for parts. Where 'A' and 'B' are two tracks inside one accelerator pedal module or one electronic throttle body, the tracks are not separately serviceable and the repair is the complete assembly. The exception worth ruling in first is a wiring fault — a corroded or spread terminal on the 'B' pin produces exactly this single-channel code and is repaired for a fraction of the price of an assembly. Check the circuit properly before buying the part.

Can I keep driving with P2164?

The vehicle will normally still drive, brake and steer, so this is not a stop-at-the-roadside code, but it should be dealt with promptly rather than tolerated. What you have lost is specifically the power you would reach for merging into fast traffic or pulling out to overtake, and finding that out mid-manoeuvre is the actual danger. Drive gently and directly to a workshop, skip motorway slip roads and overtakes, and check under the pedal for a trapped mat before you set off — it is both a possible cause and a hazard by itself.

OBD-II trouble code

P2164: Throttle/Pedal Position Sensor 'B' Maximum Stop Performance

The same full-travel check as P2163, run on the 'B' channel. Because 'A' and 'B' are usually the two tracks of one redundant assembly, whether the 'A' code is stored alongside this one is the most informative thing on the scan report — it separates a mechanical travel problem from a single bad track.

High severityPowertrainThrottle / IdleDrivable short-term

Quick facts

System: Powertrain
Category: Throttle / Idle
Severity: High severity
Drivable: Usually safe to drive short-term
Repair cost range: $0 – $900
DIY difficulty: Intermediate DIY

Part of a 6-code family

P2164 is one of 6 codes covering throttle/pedal position sensor maximum stop performance. The letter is the slot number your manufacturer assigned — it is not a physical difference, and the same letter means different things on different makes. The diagnosis is the same for every code in the family.

P2163 P2164 P2165 P2166 P2167 P2168

Read the full guide for this family →

Browse every code in P2100–P2199, or start from the full code library.

What does P2164 mean?

P2164 sets when the 'B' position channel's reading at the wide-open mechanical stop is outside the window the module will accept.

Drive-by-wire systems reference two mechanical limits rather than one. A hard stop defines fully closed and another defines fully open, and the module stores what the sensor reads at each so it can convert raw voltage into a percentage of available travel. This code concerns the open end of that pair.

The defining behaviour of any maximum-stop code is that it is latent. The closed reference is verified constantly, at every key-on and every return to idle. The open reference is only verified when something actually travels there — a driver flooring the accelerator, or the module commanding the plate fully open. A car driven gently may go weeks without exercising that end of the range, so the fault does not begin when the light comes on. It was already present and the first hard merge or overtake simply found it.

What makes the 'B' channel worth reading separately is who its partner is. On most platforms 'A' and 'B' are the two independent tracks of a single assembly — two sensors reading the same shaft or the same pedal arm, deliberately duplicated so the module can cross-check one against the other and detect a channel that is lying. That arrangement turns the rest of the scan report into evidence, and the question to ask before anything is dismantled is simple: is the 'A' code stored alongside this one?

If 'B' has failed the check on its own, the assembly it sits on evidently did reach its mechanical stop, because the partner track measuring the same movement reported correctly. That argues against an obstruction, against a damaged stop, and against a travel problem of any kind, and it argues for the individual track, its terminal, or its section of the signal circuit. A single-channel fault on a shared mechanical part is a strong, specific clue and it should narrow the work rather than widen it.

If both channels fail the check together, the opposite applies. Two independent tracks do not usually fail identically at the same moment, so a shared cause is far more likely than a coincidence — something physically limiting travel, something wrong with a supply or ground the pair has in common, or a reference in the module that no longer matches the hardware.

Beyond that distinction the causes follow the family. Something physically limiting travel: a floor mat bunched under the pedal, a failed mat retaining clip, a stray object, a damaged pedal stop, a plate obstructed at the open end. A signal path that is sound at rest and fails at the top: these sensors output a voltage that rises with travel, so the signal is highest at the maximum stop and a resistive joint's voltage drop is proportionally largest exactly there, which is why a circuit that passes every test with the pedal released can still cap the reading at full travel. And a stored reference that no longer matches the hardware, after a replacement, a reflash, a battery disconnection or a part fitted with a different output slope.

What is not a likely cause is carbon in the throttle bore, and it is worth knowing before a shop offers a cleaning as the repair. Deposits prevent a plate closing, not opening, which is why they dominate the minimum-stop codes and barely feature here.

One caution about the letter itself. It is a slot index the manufacturer assigned, not a description of a location, and there is no cross-industry table that says which physical sensor 'B' is on your vehicle. The partner-track relationship described above is the common arrangement rather than a universal rule, so confirm it against the wiring diagram for your exact year, make and model before you spend anything on the strength of it.

Common causes

Worn or drifted 'B' sensor track at the upper end of its range while the partner track still reads correctly
High resistance in the 'B' signal circuit capping its voltage at full travel but not at rest
Corroded, spread or backed-out terminal on the 'B' pin of the connector
Floor mat, failed mat clip or an object under the accelerator pedal limiting travel
Damaged or displaced pedal stop preventing the pedal reaching full travel
Throttle plate obstructed or mechanically limited at the open end
Shared supply or ground fault affecting the sensor pair, usually with the 'A' code stored alongside
Relearn procedure not performed after a sensor, pedal or throttle body replacement
Adaptations cleared by a battery disconnection or module reflash without a relearn afterwards
Replacement part with a different output slope or range than the original specification
Module holding a calibration for a different pedal or throttle assembly variant
Low system voltage from a weak battery or failing alternator limiting actuator travel

Symptoms

Reduced engine power warning with a restricted upper throttle range
Normal driving up to roughly two-thirds throttle, then nothing more
Check engine light that appeared during a hard acceleration rather than at start-up
Idle and low-speed driveability entirely unaffected
Hesitation or a flat spot only near full pedal travel
Limp mode that resets on a restart and returns when full power is next requested
The 'A' maximum stop code stored alongside, or conspicuously absent
Fault that followed a battery replacement, reflash or pedal assembly replacement
Cruise control unavailable
Throttle response that feels normal but capped rather than sluggish

Diagnostic steps

1.Read every stored code and note specifically whether the 'A' maximum stop code is present. A 'B' code alone points at the individual track and its circuit; both together point at shared travel, a shared supply or a stored reference.
2.Check the accelerator pedal area for a bunched floor mat, a failed mat clip or an object limiting travel before anything is dismantled.
3.Confirm from the wiring diagram which physical sensor your manufacturer designates 'B' and whether it shares an assembly with 'A' on this platform.
4.Ask what preceded the fault. A recent replacement, reflash or battery disconnection makes a missing relearn the cheapest and most likely cause.
5.Test the battery and charging system, since low system voltage limits actuator travel and mimics a mechanical fault.
6.With the key on and the engine off, graph the 'A' and 'B' values together while pressing the pedal slowly to the floor. Watching one track stop rising while the other continues is the clearest possible evidence.
7.Compare the 'B' value at full travel against the specification in service data rather than against what looks reasonable.
8.Perform a voltage drop test on the 'B' signal and its ground with the pedal held at full travel. A resistive joint has its largest effect at the top of the range and is invisible at rest.
9.Inspect the connector, paying particular attention to the 'B' pin — a single spread or corroded terminal explains a single-channel fault exactly.
10.If both channels failed, check the shared reference supply and ground for the pair before suspecting either sensor.
11.Run the manufacturer's relearn procedure and retest before condemning a part.
12.If the 'B' reading still caps short of specification after a correct relearn with sound wiring, replace the assembly carrying that channel and relearn again.

Repair cost

$0 – $900

Nothing at all is a realistic outcome when the cause is a trapped floor mat or a relearn that was never run after recent work. Diagnosis is $110 to $220 and is worth paying for here, because graphing both channels together is what separates a single failed track from a shared fault. A connector terminal repair, which is a common and satisfying answer to a single-channel code, is $90 to $260. An accelerator pedal position sensor or complete pedal assembly is $80 to $350 for the part and $160 to $500 fitted. A throttle body assembly is $150 to $600 for the part and $280 to $900 fitted. Because 'A' and 'B' usually live on one assembly, a genuinely failed track normally means replacing the whole unit rather than one sensor, and a relearn should be budgeted on top.

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DIY vs shop

This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.