2021 Honda HR-V: P0122 TPS Low Input – Fix Guide & Cost

What Does P0122 Mean on a 2021 Honda HR-V?

A P0122 code on your 2021 Honda HR-V tells you that the engine control module has measured a voltage below 0.2 volts from the throttle position sensor signal circuit. The TPS in a properly operating system generates a voltage signal between 0.5 and 4.5 volts that corresponds to throttle plate position. A reading below the 0.2-volt floor is electrically impossible during normal operation — it means the signal wire is shorted to ground, the connector has degraded, or the sensor itself has an internal failure. The ECM identifies this as a definitive circuit fault and responds with protective operating restrictions.

The 2021 HR-V is a 2nd-generation model powered by Honda's 1.8L naturally aspirated i-VTEC engine (designated the R18A in the HR-V). Unlike the turbocharged 1.5L engine found in the CR-V, the HR-V's 1.8L engine operates without a turbocharger, which means the thermal environment around the throttle body is somewhat less severe — the throttle body is not sandwiched between intercooler piping and the intake manifold as it is in the CR-V. However, the drive-by-wire throttle system and integrated TPS design are the same: the TPS is built into the throttle body and is not separately replaceable.

The subcompact HR-V's engine bay is tightly packaged around the 1.8L four-cylinder engine, and while the smaller displacement means less heat output than a turbocharged or V6 engine, the compact routing of wiring and hoses in this engine bay creates proximity risks for the throttle body wiring harness.

Symptoms of P0122 on the 2021 Honda HR-V

Despite its smaller size and less powerful engine, the P0122 code on the 2021 HR-V produces the same serious throttle control symptoms:

• Check Engine Light illuminated — often appearing suddenly without any preceding performance symptoms
• Limp mode activation — the 1.8L engine's output is already modest; in limp mode, the HR-V may be restricted to speeds unsuitable for highway driving
• Engine stalling — particularly at idle or when decelerating to a stop, with the smaller engine being more susceptible to stall events when throttle control is compromised
• Non-responsive accelerator pedal — in city traffic, a dead throttle pedal creates immediate hazard at intersections and during lane changes
• Rough idle and engine surge — the 1.8L four-cylinder may hunt for idle speed or run unevenly without valid throttle position data
• Hard starting after stall — the ECM may make restarting difficult after a fault-induced stall

Top Causes of P0122 on the 2021 Honda HR-V

On a 2021 HR-V that is 4–5 years old and potentially out of basic warranty, the diagnostic investigation reveals these likely causes:

1. Throttle body connector corrosion or damage (42% of cases) — On a 4–5 year old HR-V, the throttle body connector is the primary suspect. In the compact 1.8L engine bay, the connector sits in a position exposed to heat and, in northern climates, road salt contamination. Corroded or bent pins in the connector can suppress signal voltage below the ECM's minimum threshold. Connector inspection is always the first diagnostic action.
2. Integrated TPS failure within the throttle body (30% of cases) — The TPS is integral to the throttle body on the 1.8L R18A engine. Internal failure of the TPS sensor element requires complete throttle body replacement. Honda HDS connected to the diagnostic port will show live TPS voltage — a fixed reading near zero regardless of throttle position confirms internal TPS failure.
3. Wiring harness damage (18% of cases) — In the compact HR-V engine bay, the wiring harness runs in close proximity to other components. After 4–5 years of vibration and heat cycling, insulation can crack and the harness can develop shorts at contact points with metal brackets or coolant hoses.
4. ECM 5-volt reference circuit fault (8% of cases) — A fault in the ECM's 5V reference output — whether internal or caused by a short in a sensor on the same reference circuit — will artificially suppress TPS voltage. Measuring reference voltage at the throttle body connector is a key step to rule this out before replacing the throttle body.
5. Moisture or water intrusion (2% of cases) — After 4–5 years, cowl seals and grommets begin to show wear. Moisture intrusion through these degraded paths can introduce water into the TPS wiring, particularly in the Pacific Northwest or other high-rainfall regions where HR-Vs are popular.

Estimated Repair Costs for the 2021 Honda HR-V

The HR-V's smaller engine and simpler layout generally result in slightly lower repair costs than V6 models:

• Connector cleaning and terminal repair: $50–$130 at an independent shop
• Throttle body replacement (1.8L i-VTEC): $290–$480 parts and labor; the 1.8L throttle body is smaller and somewhat less expensive than V6 units
• Wiring harness repair: $150–$300 depending on damage extent
• ECM diagnosis and repair: $200–$500+

The HR-V is a value-oriented vehicle in Honda's lineup, and owners often appreciate that repair costs are somewhat lower than on larger Honda models. However, a proper diagnosis before parts replacement is still essential — connector cleaning at $50–$130 is far preferable to a throttle body replacement at $290–$480 if the connector is actually the root cause.

Urgency and Warranty Guidance for 2021 HR-V Owners

P0122 is an immediate safety concern. Do not continue driving with active throttle control failure.

For a 2021 HR-V, warranty status is a check-your-paperwork situation. If you are still within Honda's 3-year/36,000-mile bumper-to-bumper coverage or 5-year/60,000-mile powertrain warranty, the throttle body and ECM repairs should be covered at no cost. If basic warranty has expired, the 8-year/80,000-mile federal emissions warranty may still apply — the TPS and ECM qualify as emissions-control components. Check your mileage and original purchase date against these thresholds before paying for repairs.

After any throttle body or connector service, Honda's idle relearn procedure must be performed: ignition ON for 10 seconds (do not start), then start and idle uninterrupted for 10 minutes.

How AutoDetective AI Can Help

AutoDetective's AI platform can evaluate your 2021 HR-V's P0122 code in the context of this model's known electrical patterns, help you understand your warranty coverage status, and provide ZIP-code-specific repair cost estimates. For a value-oriented compact crossover, knowing the repair cost before walking into the shop is especially important.