PULSCAR ANALYSIS - P2135 (THROTTLE POSITION SENSOR "A"/"B" VOLTAGE CORRELATION) AND THROTTLE POSITION SENSOR, THROTTLE BODY AND ELECTRONIC THROTTLE FAULTS WITH REDUCED POWER IN NHTSA'S PUBLIC FILES
PulsCar analysis of NHTSA public data, October 2026.
License: CC BY 4.0
Attribution: "PulsCar analysis of NHTSA public data, October 2026."
Published alongside https://www.pulscar.io/blog/p2135-code

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Prepared October 2026. Source data: NHTSA public flat files (complaints received 1 January 2015 to 4 October 2026 - the latest received date in the files; the index of manufacturer communications) and documents downloaded one at a time from static.nhtsa.gov. The NHTSA complaint file is public: anyone can download it from NHTSA and check any number here against it.

1. Complaints (3,414)
   Scope: the code P2135 ("throttle position sensor A/B voltage correlation") with its sister codes P2136 and P2137 where the complaint ties them to the event, and a throttle position sensor, throttle body or electronic throttle fault described in the owner's words as reduced power, a stall or no throttle response, with or without a code.
   First search (2,514): every complaint whose narrative (a) names P2135, or the sister codes P2136 or P2137, by any spelling we searched (a letter O for zero, a space, hyphen or period after the P, the suffix 00, or a bare number after "code", "DTC", "error", "CEL" or "fault"), (b) names a throttle position sensor ("TPS", "throttle sensor") together with a fault or symptom word, or (c) names a throttle body, throttle actuator, electronic throttle, throttle valve, plate, motor or control together with a reduced-power or no-throttle-response wording. Nothing was sampled: every narrative the searches returned was sorted. The exact search wording is in codebook.txt.
   Independent check (900): a separate search of the whole complaint file for what the first one missed, run after the first batch was sorted (wordings in codebook.txt: "Service Electronic Throttle" messages, a throttle body diagnosed or replaced for a stall, "engine power is reduced", the ETC warning light, throttle actuator codes such as P2111 and P2112, accelerator pedal sensor wording). The check stopped at its row cap of 900 rows, and it estimated that roughly 1,000 to 1,500 more relevant narratives, mostly "Service Electronic Throttle" or ETC-light wording, throttle-actuator-code wording such as P2111 and P2112, and throttle-body-for-stalling wording, were not reviewed. Those are not sorted and not counted: every share in this study describes the sorted set only. Of the 900, the sorting counted 882 as relevant. found_by in the complaints file says which search found each complaint ("first search" or "independent check").
   Sorting: the sorting rules (codebook.txt) were written, dated and fingerprinted before any complaint was sorted; an addendum for the second batch was fingerprinted before that batch was sorted. Every complaint was sorted twice, independently, by the same written rules (columns sorting_1_ and sorting_2_). One category (B throttle body replaced; S throttle position sensor or its cover alone; L throttle cleaned or relearned only; P pedal sensor or pedal assembly; W wiring or connector; C computer or software; O another cause; K checked and cleared by a shop; U no diagnosis or repair stated; N not a throttle position-signal or reduced-power event of the kind studied) and four flags (limp: reduced power, limp mode, a wrench message or a throttle that does not respond; stall; recall: a recall, bulletin, special coverage or "known issue" notice is mentioned for this fault; returned: the same fault came back after a repair or the repair did not fix it). Each sorting saw an excerpt around the matching words, or the whole narrative when nothing matched.
   Agreement of the two sortings (before any settling or check) over all 3,414: category 90.0% (3,071 of 3,414); limp 96.7%; stall 98.3%; recall 96.6%; returned 97.1%.
   Settling: every complaint on which the two sortings differed in any of the five fields (636 complaints) was settled by one of the written rules listed in codebook.txt; the rule applied is in the rule_applied column. A consistency check then re-read 79 complaints on which both sortings agreed but whose notes used hedging words, against the rules on guesses and named causes (Rcons1 in codebook.txt): 17 changed, 14 of them to "no diagnosis or repair stated". The resolution column says "changed in consistency pass" for those.
   Result: 3,197 relevant (2,315 from the first search, 882 from the independent check), 217 not relevant. Counts are counts of complaints, not cars. A complaint is evidence that an owner wrote to NHTSA; nothing here is a failure rate.

2. Documents
   NHTSA's index of manufacturer communications lists 346 bulletins whose summary names P2135, P2136 or P2137 (12 do) or names a throttle position sensor, throttle body, electronic throttle, throttle actuator or accelerator pedal sensor together with a fault or symptom word. Not all of them could be read. Chosen, by reading the index summary: 52 that name the codes, are about the two throttle position signals disagreeing, or are about a throttle position sensor, sensor cover or throttle body procedure for reduced power, limp mode, a wrench light, no throttle response or a throttle-related stall (tier A), and 101 more where the summary names a throttle body, electronic throttle or throttle position sensor fault, recall, software flash or customer complaint of power loss, stalling, hesitation or a warning light (tier B). Not chosen: 182 entries where the throttle is mentioned in passing (a list of parts or symptoms, a manual table), idle or cleaning bulletins with no power-loss symptom, or another system, and 11 papers about heavy trucks, buses, motorcycles or unrelated faults. Index entries not chosen are not evidence of anything. The independent check added 149 more bulletins; its 107 on the throttle side were requested and its 42 about the accelerator pedal sensor were left for the pedal-sensor page.
   Files: 260 index entries were requested (153 from the first list, then 107 from the independent check); 255 of them have a file (255 files in all; 215 distinct documents once the 40 exact copies are set aside). The NHTSA index gave no downloadable file for these ids: 10057210, 10057873, 10090505, 10091139, 10097037. They are listed in documents.csv with "no file on NHTSA" in the read column and nowhere else.
   Reading: the files fall into groups of near-identical documents (revisions, copies, look-alikes). One representative of each group was read in full; the other files of the group were compared with their representative line by line (161 read in full, 94 compared; 38 of the compared files are exact copies, with the same text as another file, and the rest differ only in details such as a revision date, a model list or a part number, which the comparison recorded). 14 files whose PDF had no readable text were read from images of their pages. The document list says, for each file, whether it was read in full or compared, whether its own text names P2135 (22 files do) or one of P2136, P2137, P2138 and P2101 (77 files do), and its relevance (DIRECT: about this fault, the two throttle position signals disagreeing, or a throttle position sensor or throttle body repair for reduced power; LISTED: P2135 or a sister code is one of many in a list; RELATED: a companion code or the same symptom from another cause; NOT RELEVANT). When a reader gave two labels, the first is shown.
   Vehicle years, engines, build dates and coverage terms are as printed in the documents.
   duplicate_of marks exact copies (same text, or the same file, as another file). pdf_url is the NHTSA file address on static.nhtsa.gov.

3. Owner-reported amounts (254 figures in 238 complaints)
   One written inclusion rule (fixed before the figures were decided): a dollar figure is included when the owner states it as a price, charge, bill or quote for diagnosing, repairing or replacing the throttle body or throttle actuator, the throttle position sensor or its cover, the accelerator pedal sensor or assembly, their connector or wiring, the engine computer for this fault, a throttle cleaning or relearn, or a diagnostic fee for this reduced-power, stall or P2135-P2137 event, on that vehicle. Excluded: mileage written as "NNk"; vehicle value, payments, trade-ins or refund requests; repairs of other systems; totals that mix this fault with other work unless the owner attributes the figure to the throttle or pedal part; restatements of a figure already counted in the same narrative; hypothetical figures and other owners' costs; towing fees. Status comes from the owner's own words (paid, billed, quoted, offered); group is throttle (throttle body, actuator, throttle position sensor or cover), cleaning, pedal, wiring, computer, diag (diagnostic fee) or mixed. 459 candidate figures were found in the 330 relevant complaints that contain a dollar figure and 205 were excluded, each with its reason (p2135-excluded-figures.csv). Figures are what owners wrote, not audited invoices.

4. Limits
   The complaint file holds the cases where an owner wrote to NHTSA, in the owner's words, with no verification; owners whose trouble ended are mostly not in it. The shares reported describe the sorted complaints, not all cars, and no rate of failure can be computed from them. The independent check stopped at its row cap (900) and estimated that roughly 1,000 to 1,500 further relevant narratives (mostly "Service Electronic Throttle" and ETC-light wording, throttle-actuator-code wording such as P2111 and P2112, and throttle-body-for-stalling wording) were not reviewed, so the set is certainly incomplete and every share describes the sorted set only. Only 79 relevant narratives print P2135 themselves (44 Chevrolet, 8 Ford, 4 GMC, 4 Hyundai, 4 Harley-Davidson, 3 Nissan, 12 other makes); the rest describe the event in words, which is why the set is built on wording as well as on codes. The two sortings first saw only an excerpt around the matching words; category agreement between them (90.0%) is lower than for the yes/no questions, which is why every disagreement was settled by a written rule and why the article reports the share of complaints where no cause was stated. The document set holds what NHTSA's index lists and what could be read; a maker paper that is not in the index is not in it, and 5 chosen index entries have no file to read. The accelerator-pedal-sensor bulletins found by the independent check (42) were not read. The recalls table and the investigation summaries were not part of this set.